In treating depression and anxiety, just over half of all clients respond. Monitoring and obtaining early client feedback can allow for rapidly adapted treatment delivery and improve outcomes. This study seeks to develop a state-of-the-art deep-learning framework for predicting clinical outcomes in internet-delivered Cognitive Behavioural Therapy (iCBT) by leveraging large-scale, high-dimensional time-series data of client-reported mental health symptoms and platform interaction data. We use de-identified data from 45,876 clients on SilverCloud Health, a digital platform for the psychological treatment of depression and anxiety. We train deep recurrent neural network (RNN) models to predict whether a client will show reliable improvement by the end of treatment using clinical measures, interaction data with the iCBT program, or both. Outcomes are based on total improvement in symptoms of depression  and anxiety , as reported within the iCBT program. Using internal and external datasets, we compare the proposed models against several benchmarks and rigorously evaluate them according to their predictive accuracy, sensitivity, specificity and AUROC over treatment. Our proposed RNN models consistently predict reliable improvement in PHQ-9 and GAD-7, using past clinical measures alone, with above 87% accuracy and 0.89 AUROC after three or more review periods, outperforming all benchmark models. Additional evaluations demonstrate the robustness of the achieved models across (i) different health services; (ii) geographic locations; (iii) iCBT programs, and (iv) client severity subgroups. Results demonstrate the robust performance of dynamic prediction models that can yield clinically helpful prognostic information ready for implementation within iCBT systems to support timely decision-making and treatment adjustments by iCBT clinical supporters towards improved client outcomes. Depression and anxiety are primary drivers of disability worldwide . TreatmeUsing technology allows supporters to gain information about clients’ engagement with the treatment and potentially to intervene based on this information. This is commensurate with the Feedback-Informed Treatment (FIT) paradigm  that buiIn the case of depression and anxiety, just over half of all clients are expected to respond to treatment –20. InsiRecent years have begun to see the development of machine learning models for risk stratification or prediction of outcomes from treatment where research is at an early stage when using only baseline data. Still, more sound evidence exists when using routine outcome monitoring data –25. To dIn this work, we present the analysis of a large clinical sample of 45,876 mental health clients for predicting clinical outcomes. Our work leverages some unique opportunities afforded by iCBT interventions, which capture real-time data of client interactions with psychotherapy treatment alongside any changes in clinical symptoms over time. This scale of data also enables the application of a deep learning (DL) framework, which has been shown to achieve state-of-the-art performance in many applications with sequential data, including clinical time series . DL methOur analysis aims to demonstrate the feasibility of developing robust classification models using DL for the early prediction of treatment outcomes. Furthermore, within the context of an iCBT intervention for the treatment of depression and anxiety, our research investigates: (i) what user data (in what combination) is most informative within such models, (ii) how early within treatment we can achieve predictions robust enough for use in clinical practice, and (iii) how well do the best-performing models generalize to other data populations.This study leverages de-identified clinical measures and iCBT program interaction data from SilverCloud Health. This evidence-based, online self-administered platform delivers low-intensity iCBT alongside feedback from trained clinical supporters. Within the UK, SilverCloud services are predominantly accessed via client referrals from their GP or other healthcare professionals to IAPT , a program that offers talking therapies to adults to help overcome depression and anxiety. IAPT offers treatment within a stepped care service model that ensures that the most effective but least resource-intensive treatment is delivered first, and care is only stepped-up to more intensive face-to-face treatments if required . In thishttps://www.instituteforapprenticeships.org/apprenticeship-standards/psychological-wellbeing-practitioner), typically graduate psychologists, with further training in low-intensity CBT-based interventions, including iCBT. Their support involves reviewing the engagement their client achieves from week to week and writing feedback to the client on their work, aiming to provide person-centred care that ensures good client experience and desired clinical outcomes.Amongst the most popular and most accessed is the “Space from Depression and Anxiety” program. For our data-intense analysis, we considered all clients enrolled in this program between January 2015 and March 2019. The program consists of eight core modules covering fundamental CBT principles for treating symptoms of depression and anxiety. Content is delivered using textual and audio-visual materials, interactive tools  and personal stories. Clients receive access to the iCBT program for up to 6 months; however, the core treatment is centred around 8 review periods , during which clinical supporters guide clients. These clinical supporters are a specially trained cohort of Psychological Wellbeing Practitioners . Since this study does not obtain information through intervention or interaction with SilverCloud users and only uses secondary, fully de-identified data, it is not classified as human subjects research and, therefore, exempt from IRB review (Definition of Human Subjects Research: https://grants.nih.gov/policy/humansubjects/research.htm).All users in this study consented  for their de-identified data to be used in analyses for routine service evaluation and improvement. Matching the terms and conditions of the service, and user consent, permits the analysis of anonymous data for research purposes and improves the treatment platform’s effectiveness and service tools. Users were informed that this analysis might include profiling, machine learning or other techniques. Where individual-level data is used, additional safeguards such as anonymisation, use of pseudonyms (pseudonymisation) and limiting the set of individual data used (data minimization) are in place  timestamped entries for each client interaction with the iCBT program. Together, these form the input features  that are fed to our DL framework for predicting client outcomes  omes see .individual component questions and total scores for the nine-item Patient Health Questionnaire (PHQ-9) for depression  [not at all) to 3 (nearly every day), with higher scores indicating more severe depression or anxiety symptoms.The clinical measures comprise both the l score)  and the l score) . These asection of the program that the client used, which can be Content pages that the person views; the use of interactive therapy Tools; their viewing or writing of a Journal; visiting their user Profile page; or whether they interacted with their supporter as part of the Review process. In addition to the program section, the data logs also include the types of actions taken concerning these sections. For example, the client can ‘view’, ‘bookmark’ or ‘complete’ treatment Content. For ‘Content’ and ‘Tools’ actions, the data also included a topic id and tool id specifying the content or tool accessed. The combination of section-action-topic/tool id taken together  define a set of 1133 possible unique interactions that a client can take in the iCBT program. Thus, as our final feature set, we have the count of each of the 1133 unique iCBT program interactions  that a client performed within a given review period. We explain what constitutes a review period next.We had the following information for the client’s interactions with the iCBT program. We have data on the review periods as our prediction points: the SilverCloud platform is configured such that a review period begins with the client completing one set of clinical measures  that are assigned to them by their clinical supporter. Review periods can therefore be seen as a proxy for time, on average 1.8 weeks in duration  imputation to handle label censoring due to user dropout. Evaluation of predictive performance is based only on time points up to and including the last available measurement for each user. Overall, approximately 26% of users included in this study experience reliable improvement in PHQ-9 and 38% experience reliable improvement in GAD-7, where the majority of these are users with higher (moderate to severe) baseline symptom scores . RNNs are a class of deep learning methods designed to model sequential data or time series data. Unlike traditional feedforward neural networks, RNNs have connections between the neurons that form directed cycles, allowing them to maintain a hidden state or "memory" of past inputs . This maWe investigate RNN models trained on our outcomes of interest , using four different combinations of the feature sets :each of the 1133 unique iCBT program interactions (I);Counts of Q);Early total PHQ-9 and/or GAD-7 questionnaire scores (Qc); andAnswers to individual PHQ-9 and GAD-7 questionnaire component question items (I+Q).Combination of (i) iCBT program interactions and (ii) total clinical scores  using aexplicitly use the input data’s sequential nature. As an additional benchmark, we implement exponential moving averages (EMA), a naïve trend-following algorithm, for predicting reliable improvement. The EMA forecasts the expected subsequent clinical measurement and uses this to generate a binary outcome label. The RNNs and benchmark models were built on the training set. Feature and model selection was based on the results from the validation set. The final model was evaluated on the held-out test set and several external cohorts. The models were trained and tested on the AzureML infrastructure in Python 3.7. RNNs were implemented using PyTorch.We also implemented several benchmark classification methods to compare against the predictive performance of the RNNs: logistic regression (LogR), random forests (RF), and gradient boosting classifiers (GBMs). These models form the basis of iCBT outcome prediction models in existing literature , 29, 42,PHQ-9 = 71.15%, RNN-IGAD-7 = 60.93% accuracy). Interestingly, the best-performing models (RNN-I+Q), built on significantly higher-dimensional data, only marginally outperform the RNNs built on total clinical scores alone (RNN-Q). Similarly, using individual score components (RNN-Qc) instead of the total score does not provide any gains to the prediction task, yielding slightly lower accuracies for PHQ-9 and GAD-7 outcome prediction.To investigate the most informative features in the prediction of treatment outcomes, we trained RNN models on the four different feature sets  described previously and reported the overall performance of these models on our validation dataset . The RNNTo understand the clinical applicability of the predictive model, we also report performance at various operating points trading off sensitivity and specificity, focusing on regions of high specificity . While RNN-I+Q consistently performs best for PHQ-9 and GAD-7 improvement prediction, gains over RNN-Q are limited, particularly in regions of high specificity. This, together with the fact that RNN-Q is a much more parsimonious model with fewer data requirements, motivates the use of RNN-Q over RNN-I+Q in practice. We, therefore, restrict ourselves in subsequent analysis to models taking only the total questionnaire scores as input (RNN-Q).To further compare the performance of the RNNs with three benchmark machine learning models: LogR, RF, GBMs, as well as the results of the EMA, The overall predictive performance of RNN-Q on our test set for PHQ-9 (82.37%) and GAD-7 (77.92%) is summarized in The solid predictive performance for both PHQ-9 and GAD-7 outcomes symptom subgroups motivates closer examination of the prediction errors that occur to interpret model behaviour. Figs Finally, we evaluated the models performance on several external datasets across UK and US settings and for different iCBT programs. The availability of coherent, high-fidelity digital engagement data  and clinical outcome measures, as part of one of the largest datasets available for a clinical sample receiving internet-delivered cognitive behaviour therapy (iCBT), supported the development and evaluation of a deep learning framework for the prediction of treatment outcomes. This allowed us to counter many modelling limitations inherent to the classical statistics and machine learning approaches seen in prior work. Our best-performing models, based on total questionnaire scores of PHQ-9 and GAD-7, consistently predicted reliable improvement changes in clinical symptoms with above 87% accuracy and 0.89 AUC early during treatment (after three or more review periods). Notably, we achieve above 66% sensitivity for PHQ-9 and 70% for GAD-7 when designing for over 95% specificity , which is crucial to the utility of these predictions in clinical decision-making. While the limited prior work with large-scale observational iCBT data and variations in client selection criteria or outcome of interest makes direct comparisons challenging  , to our Having explored different feature sets in training RNN models, we found that the RNN based on input features combining total clinical questionnaire scores (Q) and iCBT program interaction data (I) achieved highest accuracy, outperforming those built on either one dimension or using individual score components instead of total scores. This may be attributed in part to increased overfitting, as well as the significant heterogeneity across the client population in symptom profiles and, in turn, which symptom changes contribute most to reliable improvement for different client subgroups, making it challenging to outperform the use of aggregate scores in predicting the defined outcomes. We also found in our analysis that iCBT program interactions, though a rich source of data on the platform, yield noisy predictors when taken alone as input, and contribute little additional predictive value to use of just clinical measures. One reason may be that program interactions, as a proxy for treatment engagement, contribute to outcomes via psychological change. This contribution itself will be represented within the outcome data of previous weeks, limiting the value of including interaction data separately. There may also be opportunities for different approaches to learning representations for program interactions. In our work, we encoded these as 1133 unique section-action-content sequences, which may not be the right granularity to extract meaningful patterns. Possible directions for future work include defining interactions based solely on the treatment section, grouping therapy contents by overall theme, or identifying the unique treatment components that contribute to behaviour change.Content pages themselves carry little information about the extent to which the client may attentively read and understand that content). While the relationship between platform interactions and outcomes is likely complex [On the other hand, information may be lost by representing program interaction solely on aggregate counts: modelling instead of temporal patterns in platform use within each review period may be more informative; the RNN architecture provides a flexible, high-capacity framework for such exploration. Furthermore, we must acknowledge that within this digital treatment set-up, it can be harder to separate between a client’s interactions with the digital platform and their engagement with treatment , from which point our models consistently achieve above 87% accuracy and 0.89 AUROC whilst leaving a clinically actionable time window for therapy that typically lasts eight review periods. However, at the same time, this restriction to a minimum of three review periods means that a significant proportion of clients , who might drop out, change or complete the program ahead of this time, would not be predicted for in practice. Future studies are needed to explore appropriate “prediction accuracy–client inclusion” trade-offs, and how they impact clinical utility during the provision of support, especially in the broader context of feedback-informed psychotherapy, where expected treatment response models typically require just two assessments .In any clinical application of machine learning, we need to be mindful of the potential harm of prediction errors. In the context of feedback provision within iCBT, there is general agreement among clinical experts that false positives must be minimized, as these constitute clients that need extra help and may be at risk of not receiving it, potentially delaying recovery. On the other hand, false negative predictions mean that the model predicts that a client not to achieve reliable improvement when in fact, they do. False negatives can disrupt a client’s treatment journey if they cause unnecessary or unhelpful adaptations–for example, the client is referred to more intensive care when they didn’t need to be–leading to poorer client experiences and misdirection of limited resources. However, for most negative RI predictions , clinicians described that they would work harder to identify the clients’ difficulties and treatment needs, meaning that false negative errors may not come to weigh in as much as false positives (not receiving extra help when needed), which is why we chose to restrict our model specificity to above 95% , at the expense of a higher false negative rate. Despite such adjustments and overall low error rates, it remains paramount that clinicians are carefully educated about the probabilistic nature of prediction models and their potential for errors so that they can appropriately interpret and use the provided information. This is particularly important given the heterogeneity in treatment response and potential fluctuations at an individual level, particularly in cases where abrupt changes in symptom trajectories may occur, requiring clinicians to balance assessments of the predicted outcomes with their professional expertise. Future research must carefully assess the appropriateness and real-world implications of this chosen threshold/ trade-off and guide necessary adaptations.There are multiple ways in which outcomes can be defined to inform clinical decision-making including risks of symptom deterioration; chance of recovery or remission; specific score change; mental health trend; or, as in this case, a significant reduction in symptoms. The focus on reliable improvement was a deliberate choice as it is an established metric for measuring the success of treatments delivered in the IAPT program, the context in which this work is focused. However, we acknowledge that there are controversies and a lack of agreement in determining a good threshold for assessing improvement in mental health. Further, we decided to predict a score change ‘threshold’ rather than the change in the score itself (a more sensitive measure). We found the threshold to provide a less ambiguous signal that a client might be at risk of not improving significantly (negative RI prediction). Furthermore, in a subsequent, planned deployment study (see below), we decided not to present predictions for patients with scores below ‘caseness’, for whom it is more difficult  to achieve RI, which makes negative RI predictions most probable. Yet, those predictions are less likely to indicate poor patient progress or need for more support, as these individuals are already in the desired score bounds of recovery or remission.Furthermore, with the prediction models based solely on clinical scores, we acknowledge that no further insights are given into the potential mechanisms of suggested treatment failures, nor are concrete actions proposed for how clinical supporters may address any treatment difficulties. Nonetheless, and in line with other recent research on the dynamic prediction of treatment outcomes , we consall users with highly heterogenous platform use (many of whom may complete treatment content or achieve reliable improvement before the full intended length of treatment), our priority was to be as inclusive as possible in our analysis, requiring a minimum of just two clinical measurements. Additionally, there is considerable scope for further work to better understand outcome prediction over the course of treatment with this richer dataset. For example, previous psychotherapy research has shown how clients who improve early in therapy and make sudden mental health gains [Another limitation inherent to the observational setting of this study is that like previous works , our anath gains  tend to th gains . If earlIn addition to considerations of model robustness, several practical implications need to be realized to introduce machine learning insights successfully into real-world clinical workflows . We regahttps://www.isrctn.com/ISRCTN18059067) is being designed to investigate the effectiveness of feedback-informed iCBT treatment through DL algorithms in improving symptoms of depression and anxiety, delving into clinicians’ perception on acceptance of these models, their subjective experience with the model outputs, and ultimately their potential to impact the provision of support and improve clinical outcomes.The integration of the prediction models within the supporter user interface further paves the way for real-world studies to assess the impact of introducing robust and reliable DL methods into clinical practice, intending to support clinicians in making early and necessary treatment adjustments to promote a favourable therapeutic response in the greatest number of clients. Following on from this research, a randomized controlled trial (Multiple studies assessing the benefits of feedback-informed therapy (FIT) have demonstrated how providing therapists or clinical supporters who assist the person undergoing treatment with access to feedback on expected client outcomes from treatment can improve treatment success and prevent deterioration, especially in clients with poor prognoses. Expected treatment response models are the methodological standard for assessing treatment outcomes in psychotherapy interventions, with few studies investigating the use of machine learning for the dynamic prediction of desired treatment outcomes. Within iCBT contexts, predictive models have been built on modest and selective samples (ranging from <100 to a few thousand users) and have typically involved post hoc analysis of RCT data and miscellaneous data sources, with mixed results. Reported accuracies range between 55–83%; however, different means of computing those and variations in the underlying treatment programs make any direct comparisons challenging.This study demonstrates the feasibility of using a deep learning (DL) framework to achieve robust, dynamic outcome prediction models. DL methods achieve state-of-the-art performance in many settings, given their ability to handle high-dimensional inputs and model complex, non-linear patterns in unstructured data with limited feature engineering. Deep RNNs provide a natural framework for modelling and making predictions given sequential data. The models presented here, based solely on routinely collected clinical outcome measures of depression and anxiety symptoms, yield high accuracies early into treatment (>87% after just three review periods), outperforming several other machine learning and advanced statistical methods. They also show generalizability to data from different iCBT programs, geographies, and demographic groups.Methodological implications for the current work depart from previous limitations in evidence in two ways: first, by using a large-scale dataset in training and validation that closely matches the intended implementation context and second, by employing a high-capacity DL framework to deliver robust, dynamic outcome prediction with high accuracy. The clinical implications of these models in digitally delivered psychotherapy services include enabling the near-term deployment and clinical study of such models within iCBT care that already routinely collect clinical outcome measures and employ digital review practices. This moves the field of precision psychiatry one step closer alongside many paths that seek to enable clinical supporters to prioritize better and adapt real-time interventions for clients with the greatest unmet need.S1 File(DOCX)Click here for additional data file.S2 File(DOCX)Click here for additional data file.S3 File(DOCX)Click here for additional data file.S4 File(DOCX)Click here for additional data file.S1 AppendixFig 1. User distribution and reliable improvement over time. Top figure: Distribution of time from enrolment to nth review; bottom figure: Counts of users at each review period. Fig 2. Kaplan Meier curves modelling reliable improvement events in PHQ-9 and GAD-7 for clients with different baseline severity. Survival probability corresponds to the probability that sustained reliable improvement is not achieved by a given timestep in the treatment program. A steeper drop in survival probability can be interpreted as higher rate of reliable improvement in that subpopulation.(DOCX)Click here for additional data file.S1 DatasetThese data sets correspond to the results shown in (ZIP)Click here for additional data file.


Skeletal muscle comprises long, cylindrical muscle fibers that are multinucleated and striated, i.e., they appear striped under a microscope . SkeletaHogg et al.), introduce a novel method to rapidly isolate functional mitochondria , and review the role of exercise and mitochondrial mechanisms in sarcopenia  and the effect of acute exercise on muscle protein turnover .Skeletal muscles can modify their size in response to use  and thisHogg et al. unveiled a new mechanism for regulating skeletal muscle dynamics through TCAP-1 action. TCAP-1 modulates energy metabolism in skeletal muscle via an insulin-independent pathway, which affects contractile kinetics through changes in Ca2+ dynamics and ATP production. The authors identified interactions between TCAP-1 and LPHN-1 and LPHN-3, which activates G-protein-coupled PLC, leading to subsequent changes in intracellular IP3 and DAG levels. Additionally, TCAP-1 increases cellular energy availability by promoting glucose importation into cells, likely due to increased GLUT4 expression.Younis et al. presented a new method for rapidly and efficiently isolating intact, respiring mitochondria from cultured skeletal muscle cells and murine tissue. This protocol offers high yield and purity of mitochondria with minimal contamination from other cell fractions by using nitrogen cavitation and rapid differential centrifugation to lyse cell membranes and isolate mitochondria. Further, this method allows for low variation in respiratory control ratio, with a ± 0.2 and 0.8 standard error of mean in isolated mitochondria from tissue and cells, respectively, making it highly suitable for high-resolution respiratory studies. This new protocol offers a significant advantage for researchers working with skeletal muscle tissues, particularly for respiratory studies and proteome analysis. The protocol will facilitate downstream mitochondrial evaluation, with important implications for advancing our understanding of human health and disease.Alizadeh Pahlavani et al. provide a thorough explanation of exercise intervention and mitochondrial mechanisms in sarcopenia muscles. This article reviews the evidence linking physical inactivity, reduced antioxidant defenses and impaired mitochondrial function in sarcopenia. This review also explains that age-associated disruption in multiple mitochondrial quality control processes, including mitochondrial biogenesis, fusion, fission, and mitophagy are important contributors to sarcopenia. This review highlights exercise as the most effective way to improve mitochondrial function and biogenesis, as well as to reduce oxidative stress in aging muscles. Exercise can activate signals that increase the expression of critical genes involved in mitochondrial biogenesis , thereby improving mitochondrial biogenesis, which is essential for preserving muscle function in the elderly. Alizadeh Pahlavani et al. also review the evidence that exercise positively impacts mitochondrial dynamics (fusion and fission) and mitophagy, which are mechanisms that likely contribute to improving mitochondrial and muscle function in the elderly. Overall, the article describes in detail how sarcopenia is a complex condition involving oxidative stress, impaired mitochondrial function, and impaired mitochondrial quality control processes, and illustrates how exercise can combat sarcopenia, by increasing both mitochondrial and muscle quality, thus improving overall health and wellbeing.Sarcopenia, the loss of muscle mass and function in the elderly, significantly contributes to reduced quality of life in older individuals . AlizadeHajj-Boutros et al. details the mechanisms involved in muscle protein turnover after acute exercise, focusing on the acute effects of resistance exercise (RE) and high-intensity interval training (HIIT) on muscle protein synthesis and breakdown. The review notes that older adults generally have a reduced response to exercise compared with younger individuals, with a subtle increase in their muscle protein synthesis (MPS) rate following an acute bout of exercise. The review describes the effect of RE on MPS and the signaling pathways involved, such as insulin-like growth factor-1 (IGF-1) and its downstream targets, which increase MPS. RE is also a potential activator of the integrin pathway and is involved in MPS through extracellular signal-regulated kinase (ERK1/2). Reduced stimulation of both pathways might underlie diminished or delayed MPS in elderly adults. Elderly adults can still gain muscle mass through RE, but the process is slower due to a decreased ability to respond to exercise stimuli. RE and endurance exercise (EE) result in different muscular and cellular adaptations and the duration of exercise determines the positive effects induced by RE and EE. In older adults, HIIT can induce muscle hypertrophy to a certain degree by potentially stimulating MPS, while RE + HIIT can improve muscle strength, functional capacity, and aerobic capacity. Further, the combination of RE + HIIT significantly increased markers of mitochondrial biogenesis compared to RE alone, but downstream signaling molecules were not affected, indicating attenuated protein synthesis. Overall, examining the individual response to exercise has become more complex, especially in aged populations, and predicting how people will respond to exercise is challenging. This review suggests further research is needed to examine the effects of RE + HIIT on changes in muscle mass.The review article by This Research Topic provides fundamental insights into the determinants of muscle plasticity and mitochondrial activity. These research findings hold significant promise for developing therapeutic strategies to promote and enhance muscle health. Furthermore, this Research Topic contributes to understanding the intricate molecular mechanisms that govern healthy mitochondrial function in muscle and the complex processes underlying sarcopenia and protein turnover in skeletal muscle.


Adult neurogenesis supports important brain functions, such as learning and memory, and its decrease during aging may contribute to the cognitive decline of the aged brain. This Collection provides insight into the role, regulation, and age-associated reduction of adult neurogenesis, by gathering studies investigating this process in different model systems, ages, and brain regions. SGZ neurogenesis supplies new granular neurons to the dentate gyrus, participating to hippocampal-dependent memory2.Adult neurogenesis is well established in rodents, where the integration of adult-born neurons into neural networks contributes to brain plasticity. In these animals, the main adult neurogenic sites are the ventricular-subventricular zone (V-SVZ) of the lateral ventricles, and the subgranular zone (SGZ) in the hippocampal dentate gyrus. These regions harbour neural stem/progenitor cells (NSPCs) that generate neuroblasts undergoing neuronal differentiation. V-SVZ neurogenesis provides new interneurons to the olfactory bulb, which contribute to olfactory functions4. Secondly, adult neurogenesis in mice can be modulated by external stimuli that affect cognitive performance, such as diet and physical exercise6. Nonetheless, the existence and therapeutic potential of adult neurogenesis in humans remain controversial8. Further research on adult neurogenesis is needed in different animals, brain regions, and physiopathological conditions; this Collection contributes to this effort by providing an all-round view of this process spanning its molecular mechanisms, its regulation by different stimuli and signals, and its role in brain function and aging.Two features of rodent adult neurogenesis have sparked interest from a translational point of view. Firstly, mouse aging is associated with a neurogenic decrease correlating with cognitive decline9. These observations suggest that hippocampal neurogenesis is key to sleep-dependent memory consolidation through the modulation of sleep patterns. Since sleep disturbances increase with age, this study also provides a potential mechanism linking the age-associated decrease of neurogenesis and cognitive decline.The hippocampus is a crucial cognitive structure, which makes the SGZ the most fashionable paradigm to investigate adult neurogenesis. Accordingly, mouse SGZ neurogenesis is the focus of several articles in this Collection. To address the links between hippocampal neurogenesis and function Sippel et al. exploit cyclin D2-deficient mice, in which the SGZ progenitor pool is depleted, to show that the abrogation of hippocampal neurogenesis is associated with altered sleep patterns during a spatial learning test, which correlate with the decreased performance of the mutant mice10. CIC deletion causes a decrease of the NSPC pool and an impaired maturation of adult-born neurons. Since mouse aging is associated with similar alterations, investigating CIC expression pattern and functional role in the SGZ of aging mice is a promising direction. Another hint to the molecular mechanisms potentially leading to neurogenic aging comes from the study of Schuele et al., which shows that diacylglycerol lipase alpha (Dagla), the main cannabinoid (CB)-producing enzyme, is expressed in SGZ NSPCs and, at higher levels, in granular neurons11. Dagla deletion in NSPCs and astrocytes, but not in neurons, impaires SGZ neurogenesis, suggesting that autocrine CB signaling in NSPCs may be required for their proliferation and/or lineage progression. As with NSPC activity and neurogenesis, CB levels are also affected by age12; therefore, it will be interesting to investigate whether this autocrine CB-mediated mechanism is disrupted during SGZ aging.Exploring the molecular networks regulating NSPC self-renewal and lineage progression, Hourigan et al. uncover a new regulator of SGZ neurogenesis, the transcriptional repressor Capicua (CIC), which is dynamically expressed in the neurogenic lineage, with stronger expression in NSPCs and neurons than in neuroblasts13. Bonds et al. analyse the hippocampal neurogenic cell populations in two different mouse models of T2DM, observing in both cases a reduction of neuroblasts and immature neurons14. Since IH and T2DM are associated with cognitive impairment, especially during aging, these studies have therapeutic implications.Adult neurogenesis can be modulated by several stimuli and conditions that affect cognitive performances. Two studies in this Collection show that hippocampal neurogenesis is impaired in mouse models of intermittent hypoxia (IH), a hallmark of sleep apnea, and of type-2 diabetes mellitus (T2DM). Khuu et al. analyse the effects of IH in mice during specific stages of neurogenic lineage progression, showing that IH causes an increased pro-oxidant state that impacts neural progenitors and newborn neurons, leading to a decrease in these populations that can be rescued by exogenous antioxidants15. Hwang et al. report that lactate intake can stimulate hippocampal neurogenesis in sedentary mice, without enhancing the neurogenic increase promoted by mild exercise; however, lactate can collaborate with exercise to improve the performance in spatial memory tests, and to increase the hippocampal levels of proteins implicated in neuronal plasticity16.Two other studies highlight the importance of identifying molecules capable of countering the neurogenic decline occurring during aging or disease. Arredondo et al. show that andrographolide, a plant-derived compound, can rescue the decrease in neural progenitors and neuroblasts observed in a mouse model of Alzheimer’s disease, along with the performance of these mice in a spatial memory test17. Tepper et al. describe the age-associated changes in olfactory discrimination and in olfactory bulb immature neurons in a marsupial species, the opossum, comparing these changes in female and male animals18. Although both sexes show a decreased density of immature neurons in the aged olfactory bulb, this effect is more pronounced in females, which correlates with the reduced performance in an olfactory discrimination test specifically in aged females. This study supports the idea that olfactory functions rely on adult neurogenesis in mammals and suggests that sex-dependent hormonal changes significantly affect this process. Bitar et al. investigate the human V-SVZ across the lifespan through the lens of transcriptomic analyses19. They show that neurogenesis-related genes are sharply downregulated during infancy, whereas genes associated with the immune system increase their expression with age. These results support evidence that the human V-SVZ becomes quiescent early in life17, pointing to neuroinflammation as the main driver of this quiescence, as proposed in mice20. Whether human V-SVZ neurogenesis might be activated by targeting some of these age-modulated genes is an interesting question for future research.The V-SVZ is the main neurogenic site in adult rodents based on the size of its neuronal output, but its neurogenic activity in other mammals is unclear21. Engel et al. follow up previous work showing that unsaturated fatty acids stimulate hypothalamic neurogenesis via the fatty acid receptor GPR40, by uncovering a role for p38 kinase and brain-derived neurotrophic factor in mediating the effects of GPR40 activation22. These findings may help to replace neurons with key homeostatic functions that are damaged in aging and obesity. The ability to stimulate endogenous neurogenesis may also aid the replacement of the mesencephalic dopaminergic neurons that are lost in Parkinson’s disease. Brown et al. demonstrate adult dopaminergic neurogenesis in zebrafish and its decrease during aging and in the absence of Pink1, whose mutations cause early onset Parkinson’s disease23. Pink1-deficiency also impairs dopaminergic neurogenesis in human midbrain organoids, suggesting that the mechanisms supporting adult dopaminergic neurogenesis in zebrafish may be clinically relevant.Adult neurogenesis is also present in the mouse hypothalamus, although at lower levels compared to the V-SVZ and the SGZ24. They show that NG2-cells are a heterogeneous proliferative population, which is capable of clonal expansion and dispersion depending on age and location. Although NG2-cells generate oligodendrocytes and astrocytes, but not neurons, in physiological conditions, their reprogramming might allow neuronal repair in the cerebral cortex.Finally, in those brain regions devoid of neurogenic activity, gliogenic progenitors might be amenable to reprogramming towards neuronal fates. Sanchez-Gonzalez et al. describe the adult progeny of oligodendrocyte precursors, also known as NG2-cells, of the early postnatal mouse cerebral cortexAltogether, this Collection highlights the importance of adult neurogenesis in the context of brain plasticity and its age-associated decline, and the outstanding possibilities that this research field offers for translational studies.


To report a case with branch retinal vein occlusion secondary to a retinal astrocytic hamartoma in a patient with tuberous sclerosis complex.A fourteen-year-old boy, a known case of tuberous sclerosis complex, with multiple bilateral retinal astrocytic hamartomas was followed by 6 months intervals. In his last follow-up, 6 months after initial presentation, the patient developed angiographic signs of branch retinal vein occlusion (BRVO) in the superotemporal arcade of the right eye distal to one of the retinal astrocytic hamartomas. He underwent targeted retinal laser photocoagulation. No secondary complication related to BRVO was observed during the next six-month follow-up.And Importance: Although the co-occurrence of branch retinal vein occlusion and astrocytic hamartoma may represent an incidental finding, awareness of BRVO as a possible complication associated with retinal astrocytic hamartoma helps timely diagnosis and prompt treatment of this complication, improving the visual prognosis of these patients. He was unable to communicate verbally due to his intellectual disability. Skin examination revealed facial angiofibroma, ash-leaf lesions on the trunk, and shagreen patches A–C. He wPosterior segment examination revealed multiple bilateral creamy-white appearance lesions which were compatible with astrocytic hamartomas A and B. On fundus autofluorescence (FAF)  imaging of the right eye, the large superotemporal astrocytic lesion displayed a hyperautofluorescent core with surrounding hypoautofluorescent area. The superior lesion to the above-mentioned astrocytic hamartoma showed uniform hypoautofluorescence. In the left eye, FAF revealed a large astrocytic lesion superotemporal to the fovea with central hyperautofluorescence, and a hypoautofluorescence rim, along with a smaller hypoautofluorescent lesion next to the larger lesion C and D.Spectral-domain optical coherence tomography (SD-OCT)  through the lesions was performed. All tumors were confined to the inner retinal layers and typically appeared as dome-shaped retinal thickening with disruption of the normal layers. Compatible with retinal astrocytic hamartomas, these lesions featured hyporeflective centers surrounded by hyperreflective periphery, varying degrees of posterior shadowing, and abnormal vitreoretinal interfaces.Early-phase fluorescein angiography (FA)  revealed mild hypofluorescent regions caused by tumor blockage. During the late venous phase, leakage from astrocytic lesions caused hyperfluorescence over the tumors I–L.Follow-up visits every six months were planned. Fundus examination was conducted six months after initial presentation, which revealed a slight venous engorgement located distal to the superotemporal astrocytic hamartoma in the right eye -A. The SFA of the right eye in the early phase revealed hyperfluorescent areas along the superior retinal vein distal to the tumor, which had increasing hyperfluorescence due to leakage in the late phases D and E. In the left eye's FA, no new vascular abnormality was observed. The patient had targeted laser photocoagulation of the retina in regions of leakage . At the 3This case report presents a patient with TSC who presented with an extremely unusual ocular manifestation, an astrocytic hamartoma accompanied by BRVO. After conducting a literature review in April 2023 utilizing PubMed, Google Scholar, and Scopus , we did not find any similar report.,,,Bourneville initially characterized TSC in the 1880s. It is a multisystem, autosomal dominant condition caused by mutations in either TSC1 (encoding hamartin) or TSC2 (encoding tuberin).,In patients with TSC, many ocular manifestations have been recorded, including retinal astrocytic hamartomas, achromatic retinal patches, and, less frequently, iris and ciliary body pigment epithelium hamartomas.,OCT of astrocytic hamartomas typically reveals a dome-shaped hyperreflective mass arising from the retinal nerve fiber layer in conjunction with variable retinal disorganization, posterior shadowing, and intralesional optically empty spaces (OES), appearing as so-called moth-eaten spaces, representing intralesional calcification or cavitation.Depending on their calcium content, astrocytic hamartomas exhibit hyperautofluorescence on FAF imaging.On FA, early blockage owing to the tumor mass is seen during the choroidal phase, when the intrinsic tumor vasculature begins to fill, and hyperfluorescence gradually rises throughout the arterial phase. A possible leakage may occur in the late venous phase.Multiple ocular consequences of astrocytic hamartomas of the retina have been observed. These conditions include vitreous hemorrhage, retinal vascular anomalies including neovascularization, telangiectasia, and exudation, and vitreous seeding.The mechanism of vascular occlusion in astrocytic hamartoma-affected eyes remains unknown. As Vedantham et al. also mentioned in their BRAO study, the pathophysiology of venous blockage in our case may be owing to increased resistance and therefore delayed circulation in draining veins, which increases the likelihood of vascular obstruction.,,anti-VEGF therapy without requiring any evidence of pre-retinal or choroidal neovascularization.In this case, we preferred to do targeted laser photocoagulation of the retina in regions of leakage to reduce the amount of vitreous vascular endothelial growth factor (VEGF). Previous studies have shown that astrocytic hamartomas, especially in patients with TSC, may be intrinsically associated with VEGF signaling for their structure and exudative properties independent of their ability to promote neovascularization.In light of the patient's cognitive impairment and geographical distance from the retina clinic, targeted retinal photocoagulation was deemed the preferred treatment option. It is not possible to assert that targeted laser photocoagulation represents the optimal treatment modality for this particular patient. Rather, the selection of treatment options should be tailored to the individual patient, taking into account factors such as the risk of loss to follow-up and the stratification of treatment options, such as the potential risks associated with intravitreal injection in a patient with mental retardation.The approach that was employed in the present case has specific limitations. The presence of localized vasculitis-like appearance in the superior arcade of the right eye warrants consideration of inflammatory processes that may be secondary to conditions such as sarcoidosis or tuberculosis. In cases where there is concomitant astrocytic hamartoma and vasculitis-like appearance, it is advisable to conduct inflammatory workups in this group of patients. Alternatively, employing a multimodal imaging strategy, such as optical coherence tomography angiography (OCTA), may aid in the identification of non-perfused regions in the current patient, thereby necessitating additional assessments and interventions. And finally, the patient was identified as a known case of tuberous sclerosis complex; however, due to the absence of genetic testing, the pathogenic variant of the patient could not be determined. As a result, it is unclear whether the patient belongs to the TSC1 or TSC2 variants of tuberous sclerosis complex.4Although the co-occurrence of BRVO and astrocytic hamartoma may represent an incidental finding, awareness of BRVO as a possible complication associated with retinal astrocytic hamartoma helps timely diagnosis and prompt treatment of this complication, improving the visual prognosis of these patients.Written informed consent was obtained from the patient's family for publication of this case report and the accompanying images.No funding or grant support.All authors attest that they meet the current ICMJE criteria for authorship.The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.


Checkpoint inhibitors are now widely used in the management of many cancers. Endocrine toxicity is amongst the most common side effects. These endocrinopathies differ from most other immune-related toxicities in frequently being irreversible and rarely requiring cessation of checkpoint inhibitor therapy. This review considers an approach to the presentation and diagnosis of endocrinopathies, compared to classical endocrine diagnosis, suggesting improvements to classification and treatment based on fundamental endocrine principles. These will help to align management with other similar endocrine conditions and standardise the diagnosis and reporting of endocrine toxicity of checkpoint inhibitors to improve both endocrine and oncological care. In particular, the importance of considering any inflammatory phase (such as painful thyroiditis or hypophysitis resulting in the pituitary enlargement), from the endocrine consequences , is highlighted. It is also important to consider the potential confounder of exogenous corticosteroids in adrenal suppression. Endocrinopathies are amongst the most frequent adverse events of immune checkpoint inhibitors (ICPIs). In common with all other side effects of systemic anticancer treatment, they are currently reported according to the Common Terminology Criteria for Adverse Events  .Table 1However, endocrinopathies differ from other immune-related adverse events (irAEs) in several aspects. The long-term clinical manifestations stem from the hormone deficiency, whilst the inflammatory process itself may yield only minimal manifestations. As the hormone production of an involved gland ceases completely and irreversibly in most cases, lifelong hormone replacement should be initiated, whilst discontinuation of immunotherapy and/or immunomodulation with glucocorticoid therapy is usually unnecessary, with immunosuppressive doses of glucocorticoids only rarely required where the initial inflammation causes severe symptoms. Lastly, optimal exogenous correction of hormone deficiencies is readily available, based on an early and accurate diagnosis. Thus, even severe symptoms usually resolve rapidly after the initiation of hormone replacement.These unique characteristics mean a classification based predominately on symptom severity at presentation is not helpful in guiding decisions about hormone replacement and continuation or discontinuation of ICPI therapy for endocrinopathies . Immune-These recommendations complement published guidance, including emergency management guidelines endorsed by the Society for Endocrinology , and recThe potential mechanisms underlying ICPI toxicity have been reviewed elsewhere . When coPituitary abnormalities are reported in between 1.8 and 18.3% of patients treated with ipilimumab-based regimens , usuallyIsolated ACTH deficiency (IAD) is induced by PD-1 and PD-L1 inhibition and usually manifests with weakness and loss of appetite without clinical or laboratory or radiological evidence of wider pituitary dysfunction , 21. IADA direct autoimmune damage to the adrenal cortex is relatively rare. This endocrine irAE poses a challenge in terms of evaluating the precise incidence mainly due to the lack of unified criteria for immune-related endocrine adverse effects in clinical trials and also due to incomplete endocrine profiling. Similar to the classic Addison’s disease, depletion of both glucocorticoids and mineralocorticoids yields more pronounced manifestations, including haemodynamic and electrolyte compromise compared to secondary adrenal insufficiency , 23, 24.Several cases of central diabetes insipidus have been reported so far, presenting with polyuria, polydipsia, hypernatremia, diluted urine with low/absent antidiuretic hormone levels , 26.As systemic and topical glucocorticoids are frequently used to treat non-endocrine immune-related toxicity, some patients will develop adrenal suppression. However, due to the risk of multiple toxicities, it is possible that some will also have ACTH deficiency and require long-term glucocorticoid replacement. It is, therefore, important to exclude exogenous glucocorticoid use before making a diagnosis of ACTH deficiency. If exogenous steroids have been used, then standard approaches to weaning should be followed, but if after a prolonged period there has been no recovery of endogenous cortisol production, then the possibility of co-existent ACTH deficiency should be considered. Hence, exclusion on HPA axis suppression by exogenous glucocorticoids should be the first step in the endocrine workup, requiring a careful history to include not just systemic glucocorticoids for the treatment of ICPI-related toxicity, but also topical glucocorticoids such as creams, inhalers or nasal sprays, including those used for non-ICPI-related toxicity (e.g. asthma). Where potentially suppressive doses of corticosteroids have been used , a carefAn accurate and rapid diagnosis of an HPA axis autoimmune injury is essential in the context of a cortisol-deficient cancer patient. The distinction between hypophysitis, IAD and adrenalitis has long-term consequences regarding hormone replacement therapy. Whilst hormonal deficiencies require physiological replacement, rare cases of hypophysitis accompanied by severe oedema and pressure on the optic chiasm require treatment with high-dose steroids. A recent study identified an incidence of biochemical hypocortisolaemia in 4.7% of ICPI-treated patients. Using robust endocrine criteria, 14 cases of isolated ACTH deficiency were identified, with 6 of hypophysitis , confirmWhilst ACTH stimulation tests (Synacthen® test) are used for the assessment of the adrenal glands' stress response, in accordance with the traditional endocrine dynamic diagnostic paradigm, this test is non-discriminative between primary and secondary adrenal insufficiency. A Synacthen® test may demonstrate a rise in cortisol during the first weeks of secondary adrenal insufficiency before adrenal atrophy has occurred. This is of particular concern in ICPI-induced pituitary disorders, given the often rapid onset of cortisol deficiency following checkpoint inhibitors when a Synacthen® test may be falsely reassuring. Therefore, the diagnosis of adrenal insufficiency has to largely rely on the measurement of baseline morning cortisol levels, whilst ACTH and renin levels can help to distinguish the rare cases of primary adrenal insufficiency from those with ACTH deficiency.Especially where regimens including ipilimumab have been used, a full baseline assessment of other pituitary hormones is required (TSH and free thyroxine (T4), luteinizing hormone, follicle-stimulating hormone, growth hormone, Prolactin, insulin-like growth factor 1, total testosterone for men and oestradiol for pre-menopausal women). Hypocortisolism accompanied by low or inadequately normal ACTH levels with all other anterior pituitary hormones and target glands functioning within the normal range is indicative of IAD. Two or more depleted pituitary axes, reflected by hormone levels below the normal range of target glands  and low or inadequately normal pituitary hormone levels indicate hypopituitarism (with or without hypophysitis), whilst low cortisol and aldosterone levels with compensatory elevation in ACTH levels and in renin levels or renin activity correspond with primary adrenal failure due to adrenalitis.Notably, this approach may lead to a degree of underdiagnosis in those with partial ACTH deficiency, and in the presence of symptoms compatible with adrenal insufficiency and indeterminate basal cortisol levels, insulin stress testing may be required where there are no contra-indications. Long-term follow-up data will be required to fully elucidate the long-term outcomes in those in this category.We propose that assessing patients with HPA axis abnormalities after receipt of ICPI should be focused on two principles:Management of any active inflammatory/hypophysitis phasePrompt assessment for and replacement of any endocrine deficiencies.In those presenting with severe symptoms of hypophysitis, for example, headache, urgent imaging of the pituitary is required, both to confirm pituitary enlargement and exclude other causes such as brain metastases. High-dose corticosteroids in the form of methylprednisolone are only indicated in those with pituitary enlargement that may lead to chiasma compression, as this treatment is associated with poorer oncological outcomes , and doeThose who present acutely unwell or with signs of adrenal crisis should be managed as per standard approaches, as outlined in the Society for Endocrinology guidelines for the acute management of the endocrine complications of checkpoint inhibitor therapy . This shMost patients with pituitary abnormalities from ICPI treatment are diagnosed after presenting with symptoms of either hypophysitis hypopituitarism or isolated ACTH deficiency. Although pituitary dysfunction may be detected on routine testing during ICPI therapy, there is little evidence to guide a screening strategy. All available guidelines and summary of product characteristics on ICPI-IE recommend checking thyroid function on each cycle of treatment, and changes in TSH  and freeThyroid abnormalities are amongst the most common irAEs described after ICPI therapy , 38, 39.Thyroiditis is the most common endocrinopathy, affecting 20–30% of ICPI-treated patients. It usually starts a few weeks after the initial introduction to checkpoint inhibitors, with a transient thyrotoxic phase, presumed to reflect spillage of pre-formed hormone, from the inflamed gland. Interestingly, this phase is usually less symptomatic than would be expected in other thyrotoxic states . In contThyroiditis can also present as increased uptake in the thyroid on FDG PET scanning .Of note, hypothyroidism can develop without a preceding thyrotoxic phase. Whilst this may present with symptoms of hypothyroidism, it is more commonly detected on screening, as most protocols recommend testing thyroid function with each cycle of ICPI.Rarer are reports of Graves’ disease resulting in persistent thyrotoxicosis requiring antithyroid drugs such as carbimazole , 47, 48.The CTCAE criteria for hyperthyroidism and hypothyroidism  are baseHypothyroidism, whether occurring as the first manifestation of ICPI-related thyroid disease or after a period of thyrotoxicosis, is managed as per standard approaches in the management of primary hypothyroidism . This isIn contrast, as the hyperthyroid phase of thyroiditis is usually short-lived, treatment is usually supportive. As in other forms of thyroiditis, beta-blockers such as propranolol can be used for symptomatic relief, and occasionally, patients with severe neck pain may require systemic glucocorticoids. There is a limited role for antithyroid drugs. However, in those who present with signs of thyroid eye disease or whose thyrotoxicosis persists for more than 4 weeks, we recommend checking TSH receptor antibodies and/or a thyroid uptake scan, and consider antithyroid drugs such as carbimazole if positive or in persistent thyrotoxicosis, due to the rare occurrence of Graves’ disease. In these rare cases of severe thyrotoxicosis due to immune-related Graves’ disease, it may be necessary to withhold the ICPI, at least until the thyrotoxicosis is controlled, and possibly permanently in those with significant thyroid eye disease.Symptomatic hypocalcaemia accompanied by low levels of parathyroid hormone (PTH) has been described in several case reports , 53. ICPInitial management is calcium replacement, which may require intravenous calcium infusion, and the use of vitamin D analogues, as per other forms of hypoparathyroidism . HoweverProgrammed Death-1 (PD-1)- and Programmed Death-Ligand 1 (PD-L1)-based treatment regimes can result in a rapid onset, insulin-deficient state closely resembling type 1 diabetes, although autoantibodies are detected in less than 50% of cases , 60, 61.Management is based on a careful assessment of the cause, between steroid-induced hyperglycaemia and immunotherapy induced diabetes, according to standard diabetes approaches to these conditions , 67 and The current CTCAE classification of endocrine irAEs is based on short-term symptoms rather than accurate diagnostic criteria and the implications of long-term hormone replacement. This makes accurate documentation and reporting of the severity, nomenclature and incidence of endocrinopathies challenging resulting in the under-recognition of largely asymptomatic hormonal abnormalities. This issue, if not addressed in clinical practice, will hamper the development of more evidence-based strategies for investigation and treatment, as well as studies into the longer-term implications of endocrinopathy.We therefore propose a new classification of endocrine toxicity of ICPI therapy that accurately reflects the pathology, the hormonal disturbance and the treatment . We alsoExpected benefits from the new diagnostic system:More accurate documentation and reporting of endocrinopathies.Appropriate clinical management based on long-term perspective regarding hormone replacement therapy rather than short-term symptoms.Prevention of unnecessary cessation or interruption of ICPI therapy and unnecessary corticosteroid therapy.Improved reporting and future development of trial protocols, as endocrinopathies already present an exception, where current guidelines support the continuation of ICPI, having initiated hormone replacement therapy, regardless of the grade. The proposed classification would make the development of guidelines easier as the treatment would more clearly reflect the underlying diagnosis.Enhanced confidence in clinical diagnostic coding  to facilitate improved accuracy in determining incidence, prevalence, and outcomes in prospective and retrospective real-world data analysis. Future audits of clinical practice will also be refined by clearer diagnostic criteria and development of specific diagnostic codes for ICPI-IEs. To support this, and to facilitate future audits, We propose the adoption of these new diagnostic criteria for ICPI-induced endocrine dysfunction that recognise their unique characteristics compared to other forms of irAEs and to classic endocrine diseases. The revised criteria would enable accurate assessment of different endocrinopathies, matching the required treatment, and allow care planning to occur, alongside existing management guidelines , 68.DM reports personal fees from Bristol Meyer Squibb, personal fees from MSD, personal fees from Roche. SC reports personal fees from Bristol Myer Squibb. RP, SA and KY report no declarations.This study did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.


In recent years, a paradigm shift in neuroscience has been occurring from “localizationism,” or the idea that the brain is organized into separately functioning modules, toward “connectomics,” or the idea that interconnected nodes form networks as the underlying substrates of behavior and thought. Accordingly, our understanding of mechanisms of neurological function, dysfunction, and recovery has evolved to include connections, disconnections, and reconnections. Brain tumors provide a unique opportunity to probe large-scale neural networks with focal and sometimes reversible lesions, allowing neuroscientists the unique opportunity to directly test newly formed hypotheses about underlying brain structural-functional relationships and network properties. Moreover, if a more complete model of neurological dysfunction is to be defined as a “disconnectome,” potential avenues for recovery might be mapped through a “reconnectome.” Such insight may open the door to novel therapeutic approaches where previous attempts have failed. In this review, we briefly delve into the most clinically relevant neural networks and brain mapping techniques, and we examine how they are being applied to modern neurosurgical brain tumor practices. We then explore how brain tumors might teach us more about mechanisms of global brain dysfunction and recovery through pre- and postoperative longitudinal connectomic and behavioral analyses. Traditionally, neurosurgical decision making has focused on preserving “eloquent” cortical nodes and their underlying white matter pathways . More reIn this section, we provide a brief overview of the most surgically relevant large-scale brain networks: somatomotor, language, and cognitive networks. This section is intended for a reader who is largely unfamiliar with these concepts, and references to more in-depth literature reviews for each are provided.Topographically, the somatomotor network is defined largely by the pre- and post-central gyri  that execute movement and process sensation . This neClinically, the somatomotor region has demonstrated only minimal plastic potential in adults . BecauseAdditionally, somatomotor structural and behavioral alterations associated with chemo and radiation therapies is being investigated . While tUnlike many of the canonical resting-state networks , the language network is best described functionally based on various language tasks . TopograWhile certain cortical processes  can be easily mapped intraoperatively with direct electrical stimulation , more complex and abstract cognitive processes  are morIn this section, we review several commonly used brain mapping techniques and their applications to network neuroscience. We examine brain stimulation, electromagnetic recording, and magnetic resonance imaging techniques and how they have been used to probe large networks.Direct electrical stimulation (DES) of the cortex and white matter gained popularity through the work of Direct electrical stimulation (DES) is an invaluable surgical tool, and it is the gold standard technique for identifying critical functional anatomy  intraopeFor over 30 years, deep brain stimulation (DBS) has been use to compliment single-cell and field potential recordings in the identification, mapping, and characterization of subcortical structures for conditions such as tremor, Parkinson’s disease, and dystonia . IntraopOver the last several years, there has been a shift in focus from what is being stimulated at the local level as described above  toward assessing what is being engaged at the whole-brain, or network, level. This has been fueled by the growing understanding that DBS-treatable conditions  represent different forms of brain circuitopathies or connectopathies. Recent connectomic DBS studies have examined the functional connectivity of stimulated brain regions and how these relate to patient outcomes [summarized in Cortico-cortical evoked potentials (CCEP) and cortico-cortical spectral responses (CCSR) measure spread of current along white matter pathways in response to a directly administered cortical stimulus . CCEPs aCortico-cortical evoked potentials (CCEPs) have been used to assess the effective connectivity  of the lCortico-cortical evoked potentials (CCEPs) appear to be especially effective when combined with diffusion tractography as this allows assessments of not only strength of connectivity (mV) and latency (ms), but also velocity of electrical flow (m/s) . HistoriUnique benefits to CCEPs include an ability to infer causal relationships between areas. CCEPs also appear to be less effected by edema than diffusion tractography-based measures of connectivity. Limitations to CCEPs and CCSRs largely revolve around surgical exposure, similarly to DES. Currently, there is minimal opportunity to investigate interhemispheric connections or connections between disparate areas of the brain intraoperatively. In epilepsy, however, stereo electroencephalography (sEEG) pre-resection is often used to map epileptogenic foci, and this can be done bilaterally . For a mTranscranial magnetic stimulation (TMS) is a brain stimulation technique that has gained popularity due to its non-invasiveness and general safety. An electrical current is passed through a wire coil  that induces a magnetic field strongest under the intersection of the coils, generating a focal, targeted electrical current in the cortex . To mitiIn this section, we review several common electromagnetic recording techniques followed by an overall comparison. EEG, MEG, and electrocorticography (ECoG) capture signals that derive from the same underlying electrical activity of the cerebral cortex: ionic currents generated by summated excitatory and inhibitory post-synaptic potentials in the most superficial layers of the cerebral cortex.Electroencephalography (EEG) is recorded non-invasively through scalp electrodes. Strengths of EEG include non-invasiveness and high sampling rate relative to functional MRI. Weaknesses include low spatial sensitivity and poor ability to record at depth.Electrocorticography (ECoG) is recorded invasively through subdural, epidural, or depth  electrodes. While ECoG is highly spatially specific and provides excellent temporal resolution, it is invasive and suffers from limited spatial coverage.Magnetoencephalography (MEG) records extremely weak magnetic fields of the order of femtoteslas that are generated by cortical neural activity. Specialized and expensive hardware and a magnetic shielded room to attenuate environmental electromagnetic noise are required to record magnetic activity of cerebral origin. MEG is non-invasive and highly spatially and temporally specific, but it is also relatively expensive and not available at many centers.Electroencephalography (EEG), ECoG, and MEG can all resolve dynamics of cortical activity with millisecond resolution. Because of the folded geometry of the cerebral cortex, the orientations of electrical fields generated by different patches of cortex can differ. Consequently, there are differences in the neural activity best represented in EEG as opposed to MEG. For example, EEG is more sensitive to radial electrical fields generated by activity on the gyral crests, while MEG is more sensitive to radial magnetic fields  from activity in the sulcal banks . When ECThe distance between the cerebral cortex and scalp-electrodes (EEG) or magnetometers (MEG) makes these signals less sensitive to cortical activity at higher frequencies (> 40 Hz) compared to ECoG due to out-of-phase mixing of higher frequency activity arriving at the sensor with different path lengths .While both EEG and MEG signals can be studied at the level of scalp electrodes or magnetic sensors, attribution of signal features to brain anatomy requires source modeling. This is typically not necessary in the case of ECoG signals since the recording electrodes are immediately adjacent to the cerebral cortex. Scalp potentials that are recorded as EEG require the propagation of cortically generated signals through the meninges, cerebrospinal fluid, skull, and scalp. Modeling the sources of these signals onto the cortex therefore requires detailed head-modeling that accounts for the properties of these extracerebral elements in addition to brain anatomy. Magnetic fields generated by the cortex are not significantly influenced by the properties of extracerebral tissue, however. Modeling the sources of neuromagnetic activity recorded by an array of MEG sensors is therefore more straightforward.Since the 1980s, many studies have established certain key characteristics of EEG responses to sensory input and cognitive processing: local engagement of the cerebral cortex in response to a sensory stimulus or task produces an increase in high-frequency power in the gamma band (> 40 Hz), often referred to in the literature as event related synchrony (ERS), which is simultaneously accompanied by a decrease of power in the alpha (8–12 Hz) and beta (13–30 Hz) bands, referred to as event-related desynchronization (ERD) . Functioamplitude/power, coherence, and cross-frequency coupling) are commonly examined. Numerous potential amplitude/power biomarkers exist for a variety of physiological properties. As previously noted, high-gamma (≥ 70 Hz) is thought to be associated with local synchronized neuronal firing. For example, ECoG gamma band activity increases prior to finger movement onset in the pre-motor and somatosensory areas and with movement onset in the motor cortex  activity. High gamma, specifically, is believed to represent the local synchronized activation of neurons . As suchr cortex . Other fr cortex . Likewisr cortex . Becauser cortex . For exar cortex , 2017, br cortex .interelectrode coherence. Relevant to motor behaviors, gamma band inter-electrode coherence increases in the pre-frontal cortex prior to movement onset. This corresponds to the large negative cortical readiness potential occurring prior to movement onset , more recent ECoG analyses have focused on functional interconnectedness of brain foci often measured as nt onset . Additiont onset .Cross-frequency coupling (coupling  describecoupling . This cacoupling . In phascoupling . For exacoupling .0) along with at least one 1 volume with an applied diffusion gradient   (1000) allows for modeling the both free-water and a neurally constrained diffusion tensor within a single voxel  of the brain has been a tremendous resource for non-invasively imaging cortical white matter and its directionality . Diffusi, b1000) . The b10 strokes . For the strokes . This al strokes . Obtaini strokes . In gene strokes . Additio0, etc.) . For exale voxel . Additioel  images the blood oxygen level dependent (BOLD) hemodynamic response to neural activity . fMRI haStudies examining large-scale networks using fMRI typically employ a resting-state or task-based design or combine these approaches . In the As network neuroscience advances, peri-operative mapping for brain tumor resections is also evolving . The folSince Dr. Penfield, DES has been used in standard clinical practice to map positive and negative responses across cortical and subcortical areas . One groFocal slow rhythms in EEG have been recognized with brain tumors and other structural lesions from the earliest days of EEG. In 1936 using an array of just 3 scalp electrodes, A few recent studies have applied functional-connectivity estimation methods to study peritumoral networks with EEG. Higher pre-operative local and global functional connectivity in patients with low-grade gliomas or meningiomas in the language-dominant hemisphere appears to predict worse language outcomes on 1-year follow-up . AlthougD-2-hydroxyglutarate and reduced GABAergic inhibition  nodes around tumors. An early study of broad band (0.5–60 Hz) and gamma band (30–60 Hz) MEG functional connectivity performed at the sensor level, suggested loss of functional connectivity in multiple regions with left hemispheric tumors registering a greater impact . SubsequFrom the perspective of immediate clinical applications, several studies have now demonstrated that preservation of peritumoral areas with HFC in the alpha band (8–12 Hz) based on resting state MEG can predict post-operative neurological outcomes . Such HFMagnetoencephalography (MEG) has also been used by a few groups to study the reorganization of cortical areas that support motor and language function around brain tumors before and after surgical resections, especially in patients with recurrent tumors. Detectable shifts in the location of motor representations that correlated with a frontoparietal location of the tumor, presence of motor deficits, and interval between the scans have been reported . LikewisTractography is now used routinely in many centers to identify the relationship of brain tumors to critical white matter tracts . More reSimilarly, resting-state fMRI has been frequently used to define the topography of networks associated with language and motor behavior . CommonlFunctional magnetic resonance imaging (fMRI) and diffusion tractography mapping prior to surgical resection have been reviewed previously . The revPediatric neurosurgery patients pose unique challenges for many reasons, some of which include their inability to participate in complex tasks and an actively developing brain. Unfortunately, the pediatric-specific literature on brain mapping techniques is limited and largely focused on epilepsy . PresurgThe pediatric brain tumor population is also unique in that nearly two-thirds of pediatric brain tumor patients are diagnosed with an infratentorial brain tumor. The most frequent infratentorial or posterior fossa tumors (PFTs) are medulloblastomas (40%), astrocytomas (30%), and ependymomas (10%) . Their tRecent studies have used lesion-symptom mapping to create a cerebellar white matter atlas that shows cerebello-thalamo-cerebral outflow tracts in the superior cerebellar peduncle (SCP) next to the dentate nucleus (DN) and inferior vermis are associated with impaired motor, cognitive, executive, and behavioral function .While gross total resection of posterior fossa tumors contributes to relapse-free survival , preventA decline in cognitive function and the emergence of depression can have similar and compounding effects on brain tumor patients. Either symptom can diminish independence, hinder social relationships, and/or negatively impact overall perceived quality of life . Coping primary executive dysfunction syndrome , while lesions in orbital frontal regions can result in increased disinhibition, impulsivity, and inappropriateness. Similarly, lesions in the medial frontal region can result in apathy and abulia  may provide a marker of resectability beyond the boundaries of historically “eloquent” tissue . For exaOne example of a well-studied temporary motor phenomenon is supplementary motor area syndrome (SMA syndrome), or when resection of the SMA in the posterior superior frontal gyrus results in acute impairments in motor control and speech . Most ofLikewise, connectomic techniques may soon enable the mapping, monitoring, and protection of higher-order cognitive functions. Notably, there is a paucity of studies systematically mapping connections between nodes with high fidelity functional and health related outcome measures for many cognitive processes.Additionally, there is untapped potential in combined mapping techniques. For example, concurrent TMS-fMRI  or TMS-EUsing the limited available methods to understand large-scale brain networks is characteristically like the parable of the blind men and the elephant: while each technique has been developed to examine the “elephant” from various vantage points, none is able to achieve the whole picture on its own . Here, oInvasive electrophysiological recording (ECoG) and stimulation evoked methods  have excellent signal fidelity to identify topography and connectivity, but they are limited by access. Imaging methods such as structural and functional MRIs provide whole brain perspective on topography and connectivity, but measurements are indirect, temporal resolution is large, and inferences about necessity, redundancy, and specificity often cannot be drawn. Nevertheless, by merging modalities into multi- or even omni-modal designs , the shaNotably, work in multi-modal connectomics is ongoing. Studies have already combined CCEPs and tractography, while others have combined DES with tractography and resting state fMRI . Brain tIdentification of markers of large-scale network dysfunction may lead to new therapeutic targets for rehabilitation in patients with brain tumors. For example, transcranial magnetic stimulation (TMS) combined with exercise may be a beneficial treatment in patients with tumor and radiation-related motor impairments . AdditioAlso critical is the concept of cortical topological plasticity. Previous work has demonstrated that cortical representations of language and motor function may be relocated either by natural processes such as tumor invasion  Figure  or stimuBecause of the central nervous system’s seemingly endless complexity across immense size, spatial, and temporal scales, attaining a comprehensive understanding of all its states seems virtually impossible. However, gaining enough of an understanding to help better guide decision making for individuals facing brain tumor surgery is within reach. This is the focus of laboratories such as ours that are employing multi-modal connectomic imaging techniques with longitudinal behavioral studies and intraoperative stimulation/recording techniques to better understand how brain tumors perturb neural networks and how that results in neurological dysfunction, as well as how neural networks recover after surgery and what might be done to aid in their protection or reconstitution. When studied carefully, brain tumors provide a unique opportunity to test novel hypotheses about neural network function by probing networks directly and invasively with focal disruptions and monitoring how recovery occurs post-intervention. Such research may lead to improvements in understanding how neuroplasticity may be strategically modulated to improve surgical resections and functional recovery.TB: conceptualizing, drafting, revising, and final approval. PP, AB, EA-Q, and MR: drafting, revising, and final approval. MK: conceptualizing, revising, and final approval. All authors contributed to the article and approved the submitted version.


Brain vascular health appears to be critical for preventing the development of amyotrophic lateral sclerosis (ALS) and slowing its progression. ALS patients often demonstrate cardiovascular risk factors and commonly suffer from cerebrovascular disease, with evidence of pathological alterations in their small cerebral blood vessels. Impaired vascular brain health has detrimental effects on motor neurons: vascular endothelial growth factor levels are lowered in ALS, which can compromise endothelial cell formation and the integrity of the blood–brain barrier. Increased turnover of neurovascular unit cells precedes their senescence, which, together with pericyte alterations, further fosters the failure of toxic metabolite removal. We here provide a comprehensive overview of the pathogenesis of impaired brain vascular health in ALS and how novel magnetic resonance imaging techniques can aid its detection. In particular, we discuss vascular patterns of blood supply to the motor cortex with the number of branches from the anterior and middle cerebral arteries acting as a novel marker of resistance and resilience against downstream effects of vascular risk and events in ALS. We outline how certain interventions adapted to patient needs and capabilities have the potential to mechanistically target the brain microvasculature towards favorable motor cortex blood supply patterns. Through this strategy, we aim to guide novel approaches to ALS management and a better understanding of ALS pathophysiology. Amyotrophic lateral sclerosis (ALS) is a progressive disease involving motor neurons. A neuropathological hallmark of ALS is associated with cytoplasmic inclusions in degenerating motor neurons consisting of abnormally ubiquitinated and phosphorylated transactive response DNA-binding protein of 43 kDa (pTDP-43), which can be found in the motor cortex particularly early in the course of disease . Motor nClinically, degeneration of cortical motor neurons first affects one distinct area within the motor homunculus unilaterally, which is reflected by the focality of initial motor phenotypes, classified as bulbar, left or right upper or lower limb onset . The degAlthough ALS is a rare disease, the number of affected patients worldwide is expected to increase on average by 69% range 33–116%) over the next 20 years . The sam6% over tWe here outline the concept of brain vascular health on the molecular, cellular and organ level in ALS and discuss how brain vascular health could be mediated through vascular patterns of blood supply to the motor cortex and serve as a potential marker of resistance and resilience against downstream effects of vascular risk and events in ALS. We present novel magnetic resonance imaging (MRI) techniques to detect brain vascular health and propose new targeted therapies for its maintenance and recovery. Finally, we advertise strategies for the practical management of ALS patients to implement vascular rethinking in the clinical setting.The evolving and dynamic field of brain reserve, maintenance and compensation in healthy cognitive aging has gained a lot of interest due to its role in understanding inter-individual variability in cognitive performance. The possibility of enhancement , preservation  and recruitment of neuronal resources to improve cognition is of clear societal relevance and interest . Here, wJust recently, it has become clear that preservation of systemic vascular health in aging, i.e., low cardiovascular risk and minimal cardiovascular disease leads to sustained normal cognition over time by maintaining brain metabolism . LikewisWe propose that systemic and brain vascular health could be added to the emerging concept of the exposome in ALS, i.e., the role of cumulative environmental lifetime exposures interacting with the patient’s genetic risk (gene–time–environment hypothesis) as they seem to be central to ALS risk and disease progression ,29,30.The relationship between vascular health and ALS is supported by several clinical observations and systematic studies. First, ALS patients suffer from cerebrovascular disease with significantly higher frequency than control subjects . DependiIn addition, the structure and function of the motor cortex and white matter seem to additionally be highly vulnerable to poor vascular health. A greater change in blood pressure in aging, for example, has been associated with lower corticospinal tract (CST) integrity, which in turn predicts worse downstream motor control . FurtherMore than two thirds of the general population display variations of the circle of Willis (CoW) that deviate from the expected anatomy . CoW varJust recently, we investigated the circulation of the aging MTL, which can be distinguished by the number of large arteries contributing to the vascular supply. The small terminal feeding vessels originated either from only one, i.e., “single supply” or from two, i.e., “double supply”, large arteries . Participants with a double-supplied MTL displayed better preserved temporal lobe and whole-brain gray matter volume, as well as better sustained memory and global cognitive function ,51,52. TVariable vascular supply has also been observed in the human motor cortex. The medial motor cortex is supplied by downstream vessels of the anterior cerebral artery , while the lateral motor cortex is supplied by vessels originating from the medial cerebral artery  . One posLeveraging the high-resolution capabilities of 7 Tesla (T) MRI, preliminary data demonstrated that it is possible to reproduce the postmortem results see . To thatThis observed variability in distinct vascular supply patterns of the ACA and MCA could drive the subject-specific overlap of vascular territories within as well as between the lateral and medial motor cortex. Hence, as for the MTL, one could anticipate that these vascular supply patterns might be associated with motor function and could provide insight into mechanisms of resistance and resilience interacting to ALS development. This assumption is indirectly supported by few studies, revealing (i) different effect sizes for the relationship between cortex perfusion (assessed through single photon emission tomography (SPECT)) and bulbar, upper or lower limb function in ALS, and (ii) motor cortical hypoperfusion ) in ALS (which correlated with overt motor function) without motor cortical atrophy.Mechanistically, we speculate that, in the case of double supply, an overlapping perfusion territory of the feeding arteries might preserve adequate cerebral blood flow (CBF), small vessel density and microvascular function, ensuring optimal neuronal nutrition and removal of toxic metabolites from the brain. In addition, brain areas with a single vascular supply might have less capacity to compensate for the effects of long-term exposure to vascular risk factors, thus leading to early impaired microvascular function, small vessel wall remodeling, accelerated microvascular aging, and development of lesions. Lesions, e.g., microinfarcts, are commonly found in all motor cortex layers and have been considered to follow the pattern of layer-specific arteriolar blood supply, which further suggests that vessel morphology and distribution are markers of resistance to disease ,56. ExpeAccordingly, in ALS there are several lines of evidence that molecular and cellular alterations of the central nervous system (CNS) microvasculature play a pivotal role at preclinical and clinical disease stages .ClinicalTrials.gov NCT01384162 (accessed on 7 February 2023)).ALS patients frequently harbor mutations in the vascular endothelial growth factor (VEGF) gene;  protein expression and VEGF serum levels are reduced in ALS rodent models and patients ,59,60. VFurthermore, capillary pericyte coverage and integrity are reduced in ALS models and patients, albeit some (co-)effects of aging or secondary disease have to be considered as well ,66,67. PExperimental studies in transgenic ALS mice have uncovered that microvascular cells, such as endothelial cells, pericytes, and perivascular fibroblasts, are already activated in asymptomatic and preclinical disease stages. This activation occurs with increased cellular metabolic demand, turnover and wall repair, likely indicating a period of compensation in early disease stages, which indicates the significant contribution of small vessel wall integrity to initial disease dynamics . Most liIn experimental ALS and in autopsy tissue of patients, activated perivascular fibroblasts have been found in PVS, where they secrete SPP1 (osteopontin). In ALS patients, higher SPP1 serum levels predicted shorter survival, linking microvascular alterations to prognosis ,80. EarlG93A transgenic rat model of ALS, and (ii) elevated degradation of perineuronal nets in this model after treatment with protease ADAMTS4 , resulting in increased motoneuronal degeneration [Activation of microglia following BBB leakage may lead to remodeling and even degradation of the extracellular matrix in the adjacent neuropil areas ,84, whicneration ,88.Illustrated alterations of the NVU are well in line with the huge number of experimental and human postmortem studies reporting leakage of the blood–brain and blood–spinal cord barrier in ALS  show, for the first time, that these patients indeed display a significantly greater PVS burden in vivo compared to age- and sex-matched healthy controls  as well  concepts to optimize perfusion and vascularization, which in turn could enhance microvascular collateralization, small vessel structure and function to move towards the development of advantageous supply patterns. Of note, the capability of microvascular repair is closely related to (motor)neuronal and synaptic plasticity and thus linked to resistance and resilience against neurodegeneration ,131. AndPhysical activity is a low-cost intervention in primary and secondary prevention of numerous chronic diseases  . In ALS,Several epidemiological, observational and randomized controlled studies have shown positive effects of physical activity on cognition and reduced risk of neurodegenerative diseases ,127. HowExerkines are defined as signaling substances released into the blood from different tissues in response to exercise, e.g., from skeletal muscle (myokines) or the brain itself (neurokines). They exert beneficial effects on vascular brain health through endocrine (affecting distant tissue and fostering inter-organ communication) or autocrine and paracrine (affecting the cell of origin and adjacent ones) pathways . SeveralClinicalTrials.gov NCT01384162, accessed on 7 March 2023). VEGF is an exerkine that directly stimulates endothelial cell proliferation, survival and microvascular wall stabilization. It also has neurotrophic effects, which was the main motivation to initiate its application within the clinical ALS trial [A recent meta-analysis considering randomized controlled trials of aerobic and resistance exercise training in ALS showed that patients benefit in terms of motor function, increasing their resilience to disease . HoweverLS trial . Just reLS trial . InteresIncreased development of pericyte-targeted therapies is predicted within the next 10 years. Targeting pericyte dysfunction has the potential to restore microvascular integrity, tone, perfusion and clearance ,151. PhaSenotherapeutics reduce cellular senescence and may present an innovative strategy to treat incurable diseases. They are currently being tested in several clinical trials for neurodegenerative diseases, mainly AD . SenotheIn experimental ALS models, transplantation of human bone marrow-derived (hBM) mesenchymal stroma cells and endothelial progenitor cells has been shown to promote repair and stabilization of the CNS microvascular wall, which includes an increase in pericyte coverage and leads to improved motor neuron survival and motor function . ExClinicalTrials.gov, accessed on 7 March 2023) is of particular relevance. Here, cell-based therapy is used, in which neural progenitor cells producing VEGF are directly transplanted into the motor cortex of ALS patients [G93A transgenic rats [Despite increasingly convincing preclinical evidence for the potential of cell-based therapies for NVU function and microvascular repair, clinical trials using hBM-derived cells in ALS patients have focused on monitoring the (downstream) rescue of degenerating motor neurons (reviewed in ). Hence,patients ,160. Thunic rats . Additionic rats .Overall, cell-based therapies are an encouraging approach. They have been translated from preclinical to clinical trials and offer a promising potential to target ALS pathogenesis, presumably including the involved NVU. Considering that a less invasive intravenous administration seems to be as clinically beneficial as intrathecal application, a general acceptance in the clinical setting should be achievable .EVs are membrane-enclosed carriers of damage-associated molecular patterns secreted by all types of cells and are considered biofluid markers of, e.g., NVU cell activation and dysfunction. They are secreted as a tool of cellular communication by shuttling molecules that require protection from extracellular enzymatic degradation or that lack a signal sequence, such as microRNAs (miRNAs), lipids, cytokines and chemokines . Based oThere are upcoming potential and already available therapeutic strategies to tackle microvascular dysfunction in ALS. The opportunity to prevent or treat motor cortical small vessel malfunction via application of exerkines, EVs, cell-based therapies and pericyte- or senescence-specific therapeutics provides hope that new approaches will promote microvascular health and preserve motor neuron function.The evidence presented here allows us to conclude that in ALS, motor cortical vascular supply patterns through ACA and MCA branches could play a pivotal role for disease onset and pathology spread and thus represent new factors of disease resistance and resilience in this devastating neurodegenerative disorder. Of note, vascular supply can be considered both a causal and a modifying factor in a molecularly complex disease such as ALS, where mutually several pathomechanisms play a role . Our hypThe consequent, already ongoing, identification of effective targets in the cerebral microvasculature and the NVU will become a realistic prospect for individualized therapy along with lifestyle modifications and causal cell-based treatments. The parallel refinement of novel in vivo imaging markers for depicting and monitoring brain (micro)vascular health in ALS has the potential to facilitate personalized risk stratification, e.g., indirectly through cortical supply patterns that can be determined in each individual patient. This is certainly important, as current prediction models mainly focus on clinical symptoms, which reflect already existing neuronal damage, but not necessarily presymptomatic pathology . We hereIndeed, one key question is whether vascular supply patterns represent a stable individual profile that indicates local susceptibility or whether these are modifiable and dynamic, varying throughout the life and disease span. In case of the latter, one has to consider reverse causality, in which the reduced oxygen and energy requirements of motor neuron degeneration might lead to a consecutive remodeling of the supplying vasculature, which results in a decrease in diameter and thus lower MRI visibility of supplying arteries. A project within the scope of the German research foundation-funded collaborative research center 1436 (SFB 1436) is currently investigating to what extend the MRI-detected visible supply patterns are modifiable during the lifespan, comparing young vs. old and applying spatial navigation training. To address these questions, longitudinal ultra-high-resolution MRI studies accompanying ALS patients through the disease course are required.Vascular integration has implications for the dedicated consultation and management of ALS patients, their relatives and cases with familial ALS at increased risk, e.g., due to monogenetic mutations with high penetrance . Most oAdditionally, chronic psychosocial stress (CPS) and highly covariant emotional disorders such as depression are increasingly recognized modifiers of (brain) vascular health. For example, CPS and depression have not only been related to higher cardiovascular risk but also to alterations of the brain’s endothelial transcriptome and to reduction of brain microvascular perfusion ,171. SimDepression, along with fatigue, dysfunctional sleep, apathy and irritability are very common in ALS and several patients likely experience CPS due to the critical life event of being confronted with a fatal diagnosis ,174,175.ALS patients should be informed and systematically educated about the importance of (brain) vascular health, the associated impact of vascular and mental health, and the fact that new experimental concepts are in progress that aim to maintain and restore the brain microvasculature, as pointed out above. Patients, caregivers and clinicians should closely follow developments in the  field of microvascular treatment concepts in ALS to prepare for their translational clinical application, which is just becoming a reality.