The present study investigated the effect of urban (traffic noise) vs. natural (birdsongs) soundscapes on mood, state paranoia, and cognitive performance, hypothesizing that birdsongs lead to significant improvements in these outcomes. An additional goal was to explore the differential impact of lower vs. higher diversity of the soundscapes by manipulating the number of different typical traffic sounds or songs of different bird species within the respective soundscapes. In a randomized online experiment, N = 295 participants were exposed to one out of four conditions for 6 min: traffic noise low, traffic noise high, birdsong low, and birdsong high diversity soundscapes. Before and after the exposure, participants performed a digit-span and dual n-back task, and filled out depression, anxiety, and paranoia questionnaires. The traffic noise soundscapes were associated with a significant increase in depression . Concerning the birdsong conditions, depression exclusively decreased after exposure to the high diversity soundscape . Anxiety and paranoia significantly decreased in both birdsong conditions (medium effect sizes). For cognition, no effects were observed. In sum, the present study suggests that listening to birdsongs regardless of diversity improves anxiety, while traffic noise, also regardless of diversity, is related to higher depressiveness. Moreover, for the first time, beneficial, medium-sized effects of birdsong soundscapes were demonstrated, reducing paranoia. Overall, the results bear interesting implications for further research, such as actively manipulating soundscapes in different environments or settings  and testing their effect on subclinical or even clinical manifestations of anxiety and paranoia. Until 2050, it is estimated that 68% of the world population will be living in cities2. In Europe the urbanization rate is already as high as 75%. Urbanization coincides with increasing rates of mental illness. An earlier review from 2005 came to the conclusion that about 30% of the incidence in schizophrenia may be attributed to urban factors in interaction with genetic liability and social adversity3. A meta-analysis4 shows a link between the increase of schizophrenia incidence and the increase in urbanicity, highlighting the fact that the risk for schizophrenia in the most urban environment was estimated to be 2.37 times higher than in the most rural environment. In a study investigating environmental factors known to trigger paranoia5, it was shown that urban cyclers commonly report to experience at least one state paranoia reaction, reported on a paranoia scale, in response to what the authors call an interpersonal threat situation. This was caused by the presence of potentially dangerous traffic participants, such as motor vehicle drivers. According to Ellet et al.5 the key environmental factors known to trigger paranoia include threat and ambiguity, which may be more often found in urban compared to natural environments. A recent review on depression and urbanicity reported mixed results, however with the majority of studies suggesting an elevated risk of depression in more (vs. less) urbanized areas6. Concerning mood and anxiety disorders, a review on studies conducted in Europe concludes that most studies showed elevated risks for mood/anxiety symptoms when comparing some  of the urban to rural areas7. In sum, there is hence accumulating evidence that living in urban areas is related to worse mental health outcomes.The impact of environmental influences on psychological well-being and cognition in humans have for a long time been neglected in traditional psychology. At present, human living environments are changing drastically. According to the UN 2007 was a turning point for humankind as for the first time the majority of the global population lived in urban areas8. Another study, which looked at the perceived sensory dimensions (PSD) relevant for attentional and stress recovery in green spaces, found that natural environments which are serene, provide refuge, and are rich in species diversity, as well as are perceived as highly ‘natural’, are rated as most restful9. These effects are often explained by two predominant theories. Stress reduction theory (SRT) posits that landscapes, containing vegetation, water and other aspects that provide benefits for survival, help to moderate and reduce states of arousal and negative thoughts and thus reduce the psychological and physiological symptoms of stress10. Similarly, Attention Restoration Theory (ART) states that stimuli from natural sources restore cognitive function by reducing attention demands of the endogenous attention system11.Contrary to the negative effect of urban environments on mental health, a recent study shows that increasing access to total and usable green space within the neighborhood can decrease anxiety/mood disorder treatment counts. This demonstrates the service that urban green spaces may provide for general mental health and well-being12. Man-made (urban) soundscapes  can constitute constant stressors that may impair cognitive function and well-being. Urban noise contains salient stimuli that likely trigger an alert physiological and psychological state. Corroborating this notion, a systematic review on traffic noise exposure found consistent evidence for an association between traffic noise and depression, as well as cognitive decline13. On the other hand, natural soundscapes, which are typically characterized by birdsongs, wind, or water12, could be an important source of attention-restorative and stress-ameliorating effects, as they might be implicitly associated with a safe and vital natural environment. As documented by a narrative review, birdsongs, water-, and wind-sounds have been shown to be perceived as pleasant, and to have beneficial effects on mood, arousal levels, and cognitive performance12. Importantly, in several studies that have reported positive effects of birds on human well-being, higher species diversity was a relevant factor14, perhaps because it may indicate the vitality or intactness of natural spaces. In a study across 26 countries conducted by Methorst et al.15, the authors established a relationship between species diversity of birds within a region and self-reported life satisfaction of residents of those regions. Remarkably, it was found that a 10% increase in bird species diversity raises life-satisfaction approx. 1.53 times more than a proportional rise in income15.Experimental research in the field has so far predominantly studied visuo-spatial aspects of the environment concerning mental health effects, such as by using photographs, videos, slideshows, or other visual stimuli. Other sensory modalities have been much less studied16 compared a nature vs. city soundscape condition, whereby the former enhanced participants’ performance in a dual n-back and digit span task, but did not improve mood. The present study broadly builds on the study by van Hedger et al.16 but adds the factor of diversity to the soundscapes. In addition to mood and cognition , the present study additionally focusses on state paranoia, as this is a very prominent symptom in psychosis which can be measured in a change-sensitive manner17. Furthermore, state paranoia has been shown to increase in response to traffic noise 18. However, investigating in how far natural vs. urban auditory stimuli might influence this symptom category has, to our knowledge, not systematically been studied yet. The present study thus addressed the following hypotheses: (1) birdsong (vs. traffic noise) soundscapes have a beneficial effect on mood and paranoia; (2) birdsong (vs. traffic noise) soundscapes have a beneficial effect on cognitive performance. Furthermore, it was investigated whether greater (vs. lower) diversity of bird species or noise sources within the soundscapes would be a relevant factor, modulating the effects. The outcomes  were each measured before and after soundscape exposure. For each soundscape type a low vs. high diversity version was created. This resulted in a between 2 (type: birdsongs vs. traffic noise) × 2 (diversity: low vs. high) × within 2 (timepoint: pre vs. post) randomized experimental design.In a randomized controlled experimental study using auditory stimuli, hypotheses derived from ART and SRT were tested. Van Hedger et al.type  = 78.6, p < 0.001, ηp2 = 0.461), diversity  = 3.16, p = 0.025, ηp2 = 0.033), as well as type × diversity  = 2.66, p = 0.028), suggesting that all of these factors as well as their interaction had a significant impact on the perception of soundscapes .The results of the MANOVA, revealed significant effects of type, that it only significantly affected beauty  = 168.8, p < 0.001, ηp2 = 0.378) and pleasantness perceptions  = 182.3, p < 0.001, ηp2 = 0.396), but not monotony/diversity type  = 0.06, p = 0.812, ηp2 = 0.000). Concerning the factor diversity, it only significantly affected the monotony/diversity ratings type  = 6.21, p = 0.013, ηp2 = 0.022), but not the other rating dimensions of beauty  = 0.84, p = 0.361, ηp2 = 0.003) or pleasantness  = 0.58, p = 0.448, ηp2 = 0.002). Finally, concerning the interaction type × diversity, there were no significant effects on monotony/diversity  = 0.75, p = 0.387, ηp2 = 0.003) nor beauty  = 2.84, p = 0.093, ηp2 = 0.010), but on pleasantness  = 5.36, p = 0.021, ηp2 = 0.019).Univariate follow-up ANOVAs revealed for the factor p < 0.001), with large effect sizes.For statistical details on the post-hoc tests, see Table F = 0.31, p = 0.820), or anxiety  = 0.31, p = 0.821). However, across the groups there were significant differences in state paranoia  = 3.34, p = 0.020). For details (exact group differences and descriptive baseline data), see Supplementary Table Univariate analyses of variance revealed no baseline differences across the groups in the outcome variables at baseline for depression  = 4.51, p = 0.035, η2partial = 0.015), suggesting overall changes in depressive states from pre-to-post. The soundscape type × time interaction was significant  = 32.1, p < 0.001, η2partial = 0.099), the triple interaction type × diversity × time was non-significant  = 1.52, p = 0.217, η2partial = 0.005), suggesting that diversity was not a modulating factor of the differential pre-post-change by type. Additional analyses were run to check the robustness of the effects i.e., controlling for state paranoia age, and positive symptoms which differed significantly (paranoia) or at trend  at baseline as covariates, and excluding cases who did not type in at least one digit of the auditory codeword at the end of the soundscape correctly (= listening compliance check). The results of these analyses were comparable to the above reported ones. Post-hoc examination of the effects by computing within group dependent t-tests revealed that depressive symptoms significantly increased within both the low diversity urban soundscape  = 2.64, p = 0.010, d = 0.29) and high diversity urban condition  = 4.88, p < 0.001, d = 0.59), whereas there were differential effects in the birdsong conditions with no change in the low diversity condition  =  − 1.49, p = 0.142, d =  − 0.19) but a significant decrease in the high diversity condition  =  − 2.57, p = 0.012, d =  − 0.29)  = 39.9, p < 0.001, η2partial = 0.121), suggesting overall changes in state anxiety from pre-to-post. The soundscape type × time interaction was significant  = 30.1, p < 0.001, η2partial = 0.094), the triple interaction type × diversity × time was non-significant  = 0.15, p = 0.704, η2partial = 0.000), suggesting that diversity was not a modulating factor of the differential pre-post-change by type. Additional analyses were run to check the robustness of the effects (for details see previous section), which revealed that the findings were not altered by entering the covariates and/or excluding cases with incorrect codeword (failed listening compliance check). Post-hoc within-group t-tests for anxiety revealed that there were no effects within both traffic noise conditions  =  − 1.37, p = 0.174, d =  − 0.15; high diversity: T = 0.49, p = 0.629, d = 0.06), whereas there were significant declines in both birdsong conditions  =  − 6.13, p < 0.001, d =  − 0.77; high diversity: T =  − 6.32, p < 0.001, d =  − 0.70)  = 45.5, p < 0.001, η2partial = 0.070), diversity was non-significant  = 0.50, p = 0.480, η2partial = 0.002), as was the interaction type × diversity  = 0.18, p = 0.670, η2partial = 0.001). Finally, for paranoia there were no changes in the traffic noise conditions  =  − 0.55, p = 0.583, d =  − 0.06; high diversity: T = 0.67, p = 0.507, d = 0.08), but significant decreases in both birdsong conditions  =  − 5.90, p < 0.001, d =  − 0.74; high diversity: T =  − 4.11, p < 0.001, d =  − 0. 46)  = 0.45, p = 0.720), or the according backward digit span measure  = 0.15, p = 0.962). Univariate analyses of variance also revealed no baseline differences across the groups in the cognition outcome variable at baseline for the dual n-back measure d prime  = 1.01, p = 0.388).Univariate analyses of variance revealed no baseline differences across the groups in the cognition outcome variable at baseline for the forward digit span two-error maximum length (TE_ML) measure  = 1.1, p = 0.298, η2partial = 0.004). The time × soundscape type interaction effect was also not significant  = 0.2 p = 0.662, η2partial = 0.001), as well as the time × type × diversity triple interaction  = 1.1, p = 0.296, η2partial = 0.004). The same null-finding emerged for the according backward digit span measure: time  = 0.30, p = 0.582, η2partial = 0.001), time × soundscape type  = 1.04, p = 0.308, η2partial = 0.004) and time × type × diversity  = 1.2, p = 0.278, η2partial = 0.004). For the n-back task total performance parameter, there were also consistent null-findings. There was no significant effect of time  = 0.37, p = 0.543, η2partial = 0.001) or time × soundscape type  = 0.23, p = 0.635, η2partial = 0.001) nor time × type × diversity  = 1.12, p = 0.279, η2partial = 0.004). Additional analyses were run to check the robustness of the effects i.e., controlling for state paranoia age, and positive symptoms which differed significantly (paranoia) or at trend  at baseline as covariates, and excluding cases who did not type in at least one digit of the auditory codeword at the end of the soundscape correctly (= listening compliance check). The results of these analyses were comparable to the above reported ones. At last, an aggregation of both task scores into a composite z-score, which is an established practice in the field16, did not yield a significant result either.Concerning the two-error maximum length digit span forward, there was no significant 16, who demonstrated that a natural vs. urban soundscape was related to better cognitive outcomes, but failed to demonstrate significant effects on mood. In the present study, birdsongs were contrasted with traffic noise, whereby a novel diversity factor (low vs. high number of birdsongs or traffic noise sources in the soundscapes that participants were exposed to) was introduced, and effects on paranoia were additionally tested  and paranoia, but not on cognition , were found. Traffic noise soundscapes generally aggravated depressive states , whereby these soundscapes were also perceived as significantly different in terms of diversity in subjective ratings, which were conducted as a manipulation check at the end of the study. Exclusively the highly diverse birdsong soundscape decreased depressive states . Generally, the birdsong conditions were not rated as significantly different in terms of diversity. Concerning anxiety, traffic noise soundscapes had no effect, whereas both birdsong soundscapes significantly alleviated anxiety (medium effect sizes). Finally, the traffic noise soundscapes had no effect on paranoia, whereas again both birdsong soundscapes significantly lowered it (medium effect sizes).Opposed to van Hedger et al.20. Mood recovery  or beneficial mood effects have repeatedly been reported for exposure with natural sounds22. The present study thus confirms prior findings. Moreover, to the best of our knowledge, beneficial effects of natural soundscapes on state paranoia are shown for the very first time. This finding might be explained in several ways. Birdsongs might be implicitly associated with a vital natural environment, divert attention away from  stressors, or could signal the absence of acute threat. Urban soundscapes on the other hand might trigger socio-evaluative concerns, involuntarily direct attention resulting in perceived loss of control and hence alter vigilance to potential threats which are processes proposed to elicit paranoia. However, somewhat contradicting the latter notion, the traffic noise soundscapes as used in the present study did not increase paranoia. Possibly, by adding human voices to the audio file, this effect could have been evoked. Human voices may more readily activate interpersonal sensitivity, to which a central role has been ascribed in the emergence and maintenance of paranoia23. Generally, classical learning paradigms (conditioning) might provide a framework to explain restorative nature effects. Hereby, first an unconditioned positive response occurs in reaction to nature, which gets later retrieved by similar natural cues, and can later generalize to an abstract level whereby even more abstract cues  may trigger the original response24.The beneficial effects of birdsongs in particular concerning mood and attention restoration have been previously observed16. An explanation for the null effect could be the degree to which the administration of the tasks was controlled. The current study was performed online, practice was restricted to two blocks , and hence there was little control over the degree to which subjects understood the task correctly . In addition, the online as opposed to a laboratory situation does not allow for controlling context variables or systematically manipulating baseline levels of stress or fatigue21. Besides the highlighted methodological issues with respect to the cognitive outcomes of the current study, it could be debated whether such an effect of exposure to nature on cognitive performance as measured by executive functioning tasks really exists on a population level. Support for the existence of this effect originally comes from a study in which mere viewing of pictures from nature improved cognitive performance11. This was subsequently replicated with auditory exposure to nature in the form of soundscapes using the same cognitive tasks that were also administered in the current study16. Summing up this debate there hence seems to be preliminary support for the existence of such an effect on a population level, however future meta-analyses about this effect should be carried out in order to clarify the existence of the effect.Neither urban (traffic noise) nor natural (birdsong) soundscapes had any effect on cognitive performance, which, at first glance, seems to contradict a previous study, which implemented the same cognitive tests 15 where bird species diversity in a given region was shown to be related to reported life-satisfaction in that region, the authors suggest two explanations which are also relevant in the light of the afore-mentioned result. It is concluded that the multisensory experience of birds can be a crucial factor for diversity of birdsongs to have an effect on life-satisfaction. Yet another explanation is that beneficial landscape properties in fact drive the effects, promoting both bird diversity and people’s life-satisfaction independently of one another. In the current study it might be the case that merely listening to a more diverse birdsong soundscape did not communicate the same multisensory experience than it does when people are experiencing bird diversity in a real-life situation. Furthermore, the appreciation of diversity might rely on certain knowledge or expertise, resulting in a benefit only for experienced listeners. Potentially, our sample did include mostly lay people concerning bird listening, which could partially explain the result with respect to the diversity variable . Future studies investigating this topic should aim to include some kind of expertise measurement in order to control for this factor.Concerning the fact that there was no difference between the high and low diversity soundscapes of birdsongs with respect to the effects on mood and paranoia it should be mentioned that in a study by Methorst et al.One limitation of the present study is the numerically higher percentage of males relative to females , which is a typical problem encountered in online studies. Future studies should stratify the subgroups by sex, such as to balance the sample in this regard. Furthermore, the manipulation of low vs. high diversity of the soundscapes was only partially successful. Namely, although the soundscape composition followed a logical rationale in this regard, and the subjective diversity rating the urban soundscapes significantly differed in the traffic noise soundscapes, this was not the case for the birdsong conditions. To assure stronger contrasts, and hence to be able to test the diversity hypothesis more aptly concerning enhanced beneficial effects, the contrast between the soundscapes needs to be further enhanced in future studies. In addition, mixed conditions such as urban soundscapes containing birdsongs would be a highly interesting research target, as this could more readily reflect daily life exposure situations.It remains to say that the current study made use of a non-clinical sample opening the debate if the observed effects can also be generalized to people diagnosed with high levels of e.g., paranoia. Taking into account the continuum hypothesis, which states, that psychotic symptoms which are seen in patients can also be observed in non-clinical populations, it might be the case that both populations share a mechanism by which symptoms can be relieved or improved. This remains speculative, nevertheless the current study can be seen as a pilot, exploring the existence and potential magnitude of effects, feasibility, and safety for a future transfer to a more vulnerable clinical sample. Future research could adopt the current design and investigate the effects of birdsong exposure on paranoia within a clinical sample. Such research can potentially result in low threshold environmental interventions to reduce distress in e.g., psychiatric wards or other clinical settings. In the sense of conditioning (see above), associations with natural environments might divert attention away from psychological stressors or signal the absence of acute threat. Future experiments could aim to explore if paranoia does in fact not decrease after exposure to threatening natural environments, such as the wilderness, or situations which signal the acute presence of threat, such as natural disasters.Moreover, it is important to highlight the fact, that the results of the current study cannot provide any clarification concerning the sustainability or replicability  of the effect birdsongs can have on mood and paranoia. Future research should aim to test such effects in a longitudinal and/or repeated exposure study design. Yet another limitation in the current study is the lack of a neutral control sound condition which would enable the interpretation of results with respect to a neutral condition instead of the mere comparison between a traffic condition and a birdsong condition. The use of such a neutral control group within a similar design as implemented by the current study would be a great addition for future research. Finally, although the instructions required participants to set their audio system loudness to 80%, still subjectively perceived loudness of the soundscapes could constitute a confounding factor.The present study provides evidence for the beneficial effects of birdsongs on mood  and paranoid symptoms, with the latter being shown for the first time. On the other hand, the negative effects of traffic noise were only confirmed concerning depressive symptoms. The manipulated low vs. high diversity of the soundscapes did not have a significant effect, which might in part be explained by no perceived subjective differences concerning monotony vs. diversity. Further replication in vulnerable, elevated risk- or clinical groups could be of interest to assess the magnitude of effects given pre-existing symptoms and cognitive performance deficits. In case of replication, using birdsongs as ‘soothing’ background soundscape could open interesting new possibilities in psychiatric hospitals or other therapeutic settings.25. We opted for a small effect size as a similar study as ours, conducted by van Hedger et al.16, also using a repeated-measures ANOVA data analysis approach, reported interaction effects type  by time ([2] pre-to-post exposure) on mood, whereby Cohen’s d for negative affect was between 0.36 and 0.40. These results were non-significant, as the study was underpowered for detecting small effects. The interaction effects observed concerning cognition in that paper, applying the same tests as in the present paper, were large (d between 0.71 to 0.76). Since we were interested in detecting effects on mood and to study yet unknown effects on state paranoia, we opted for and intermediate effect size between small and medium.A power calculation was conducted for an interaction effect (repeated measures ANOVA), in G*Power 3.1.9.7 with f = 0.10, α = 0.05, power = 0.90, 4 groups, correlation between repeated measures r = 0.60, resulting in a minimum required total sample size of N = 288 (n = 72 per group). According to the general rule of thumb for Cohen’s f statistic, f ≥ 0.10 < 0.25 is a small effect, f ≥ 0.25 < 0.40 is a medium effect, and, f ≥ 0.40 a large effect https://aspredicted.org/d5j7j.pdf) on 06/04/2021.The study was pre-registered at aspredicted.org  and accordingly run on the Millisecond server. Participants were recruited from the crowdsourcing platform Prolific and received 10€ reimbursement for their full participation. Adult individuals were pre-screened on Prolific  concerning fluent German language skills (as this was the study language), having no diagnosed lifetime mental illness, and having no hearing difficulties. Pre-screened individuals could then access the study, where in- and exclusion criteria were checked further. This included no regular substance or drug intake, no suicidal thoughts, or tendencies, and availability of headphones for the purpose of the study.The study was programmed using Inquisit 5After providing informed consent, sociodemographic information was assessed, including education, income, and further variables, which were assessed for potential additional or exploratory analyses, but for the sake of conciseness are not reported in this paper. Psychosis liability was assessed. For an according overview on sample characteristics, see Table N = 401 individuals started the survey. Of those, n = 76 quit during the sociodemographic assessment, n = 24 lacked pre-test data, and n = 6 lacked post-test data. These n = 106 cases were excluded from the analyses, resulting in a final sample of N = 295. Of these, some participants had incomplete post-test data .Initially, p = 0.058). The values were mostly similar and within a confidence interval range that has previously been reported for healthy individuals19. Due to the trend-level nature of the differences in positive symptom frequency, we decided to repeat the main analyses, controlling for this variable as covariate in the repeated measures ANOVAs.For detailed information and inferential statistics comparing the groups at baseline see Table For all mood and the paranoia scales, item scores were computed . This way, the interpretation of scores is facilitated, as it corresponds to the Likert-scale of the respective measure.19, in its German version, to assesses lifetime positive, negative and depressive symptoms (http://www.cape42.homestead.com/index.html). The CAPE, including the German version, has been validated extensively17. Items refer to the lifetime prevalence of specific symptoms, rated on an ordinal response scale for frequency . The total scale consists of 42 items, whereby the positive symptom scale includes 20 , the negative symptom scale 14 , and the depressive symptom scale 8 items . To test for comparative baseline levels across all groups in psychosis liability, mean frequency scores for the positive symptom subscale was used, for which Mossaheb and colleagues have provided descriptive data for individuals with ultra-high risk for psychosis (n = 84) vs without risk 19. The positive dimension (frequency) of the CAPE had excellent internal consistency in the present sample, with Cronbach’s α = 90.Psychosis-liability or sub-clinical psychosis levels was assessed using the Community Assessment of Psychic Experiences (CAPE)27. The scale contains 40 items, whereby the same 20 items are once presented in trait and once in state format. Only the latter was used in the present study. The scale differentiates between depression  and anxiety , whereby each of the subscales is assessed by 5 items. The response format is a 4-point Likert . Internal consistency (Cronbach’s α) at pre-test was good both for the state anxiety (0.85) and depression (0.86) scales.Mood was assessed with the State Trait Anxiety Depression Inventory (STADI)17. The scale comprises 3 statements , rated on an 11-point Likert-scale (each from 1 to 11) for the degree of agreement to the statement, associated distress and conviction, at present. The latter two categories were only presented if the rating of agreement to the statement was > 1 (which accordingly often results in a large amount of missing data). In the present study, only agreement was evaluated. Internal consistency at pre-test was acceptable with Cronbach’s α = 0.78.Paranoia was assessed with a brief, change sensitive state version of the paranoia checklist, which has been validated and comparable to the long, state adapted 18-item version26 [retrieved from https://www.millisecond.com] which is based on the original task reported by Woods et al.28. Two parameters are recommended for evaluation: the two-error maximum length (TE_ML) and the maximum length recalled (ML). The two-error maximum length is defined as the last digit span a participant gets correct before making two consecutive errors while the maximum length is the digit span that a participant recalled correctly during all trials irrespective of the number of errors in-between. Starting with a successive visual presentation of 3 digits, the participants need to correctly recall a by 1 digit increasing sequence of digits and reproduce it by clicking on the correct digits in correct order. After two wrongly recalled sequences of the same length, the digit span is decreased by 1 digit until the digit span length again reaches the starting point of 3. The total amount of trials is 14 making the shortest span possible 3 digits long and the longest span 16 digits long. The participants were explicitly reminded not to use any memory assisting methods such as paper and pencil. The dual n-back task, also available in the Inquisit 526 (retrieved from https://www.millisecond.com) was assessed. The task is based on the original work by Jaeggi et al.29. It consists of 4 experimental blocks demanding 2-back and 3-back level performance. While performing the task, subjects pay attention to their computer screen while also listening to a computer audio. On each trial a blue square appears in one out of eight grid-like locations around a central fixation cross, while at the same time a (German) letter is presented via the headphones. In the 2-back block condition, the subjects are instructed to press the “A” button on their keyboard when the current square position matches the square position from two trials before. Subjects are also instructed to press the “L” button on their keyboard if the spoken letter matched the letter two trials before. The same instruction, but having to match stimuli 3 trials back, is provided for the 3-back condition. In the present study, participants trained each condition once, and then went on with the experimental blocks. The performance parameter was the so-called d prime value calculated as the proportion of  + /2)/number of total experimental blocks. The highest possible d prime (greatest sensitivity) was 6.93 and the lowest was 0. Visual hits are defined as correct responses with respect to the location of the square and auditory hits are defined as the correct responses with respect to the spoken letter. Visual false alarms (FA) are defined as responses in the absence of a target in the visual domain, thus with respect to the location of the square and auditory false alarms are responses in the absence of a target in the auditory domain, thus with respect to the spoken letter.To assess digit span cognitive performance, both the forward and backward version were used, as available in Inquisit 516 study where we exchanged the “like–dislike” affective response with a more detailed aesthetic rating splitting the response up into a pleasantness and a beauty dimension. The dimension of diversity/monotony has been to perform a manipulation check on diversity for the soundscapes used in the present study.The participant’s perception of the soundscapes was assessed using a one item questionnaire per dimension . Participants were asked to report on a 0 to 100 visual scale how diverse/monotone, beautiful, and pleasant they had perceived the soundscape they had listened to during the experiment. The items have been formulated by the authors themselves while the use of an aesthetic rating of the soundscapes per se was a replication from the van Hedger et al.Steinberg Cubase10. An exemplary visualization of the resulting soundscape can be seen in the Supplementary Material  from a central European origin was used. For the low diversity birdsong condition, eight recordings from the same two species were used (common chiffchaff & wood warbler). For the high diversity birdsong condition, the same approach was chosen, but recordings from eight different bird species were used to create the soundscape . In both birdsong conditions, additionally subtle water and wind sounds were played in the background, to create a constant auditory experience. For the traffic noise conditions, sound snippets from eight car recoding’s (https://freesound.org/search/?q=city) were used for the low diversity traffic noise condition while audio-snippets from eight diverse sources of noise pollution associated with the city were used for the high diversity traffic noise condition . In both traffic noise soundscapes, a constant subtle traffic flow was audible in the background.The soundscapes for all four categories have been generated in the same way. Single sound snippets were gathered and then adapted and merged within the audio software https://osf.io/4y3vh/.To ensure that all soundscapes were perceived with a similar loudness level, all soundscapes were engineered to have a similar loudness value. The loudness values from all four conditions range between 19.4 and 27.8 loudness units relative to full scale (LUFS). All soundscapes had a duration of 6 min. Prior to the experiment the soundscapes have been presented to a small set of pilot participants rating the similarity of the audio level ensuring a comfortable audio level across all conditions. As a result, at the beginning of the experiment, participants were instructed to set their headphone loudness level to 80%. Soundscapes can be accessed openly via this link timepoint: pre vs. post) × 2 (soundscape type: birdsong vs. traffic noise) × 2 (diversity: low vs. high) interaction effect. The analyses were once run with all participants, and then only with those who entered at least one of the digits  interactions identified for any of the outcomes were followed up by subsequent detailed post-hoc-tests. To explore mean differences between the qualitative ratings of soundscapes , a one-way multivariate analysis of variance (MANOVA) was conducted. In case of significant omnibus tests indicating global differences across the qualitative sound rating dimensions, follow-up between group t-tests were conducted. Due to the exploratory nature of the study, no p-level correction was applied.Analyses were run in SPSS 27 . To test the differences of all measures at baseline, several univariate analyses of variance (ANOVA) were run. In order to test the effects of high vs. low diverse traffic noise vs. birdsong soundscapes on mood, paranoia, and cognition, repeated measures analyses of variance (ANOVA) were run testing for a 2 (η2 = 0.01 as a small effect size, η2 = 0.06 as a medium effect size and η2 = 0.14 as a large effect size30. Cohen’s d effect size was used to interpret post-hoc test effect sizes, with the corresponding rule of thumb defining a value of ≥ 0.2 as a small effect size, a value of ≥ 0.5 as a medium effect size and a value of ≥ 0.8 as a large effect size. The criteria for interpreting the effect size for Hedge’s g stem from the corresponding rule of thumb with the same definition30.The partial eta squared effect size was used to interpret the ANOVA based analyses, with the corresponding rule of thumb defining All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all participating subjects. The experimental protocol was approved by the ethical committee from the University Clinic Hamburg Eppendorf.Supplementary Information.


ETFDH gene  and no pathogenetic variant in the riboflavin (Rf) homeostasis related genes . Instead, compound heterozygosity was found in the ACAD8 gene , coding for isobutyryl‐CoA dehydrogenase (IBD), whose pathogenic variants are associated to IBD deficiency (OMIM #611283), a rare autosomal recessive disorder of valine catabolism. The c.822C>A was never previously described in a patient. Subsequent further analyses of Rf homeostasis showed reduced levels of flavins in plasma and altered FAD‐dependent enzymatic activities in erythrocytes, as well as a significant reduction in the level of the plasma membrane Rf transporter 2 in erythrocytes. The observed Rf/flavin scarcity in this patient, possibly associated with a decreased ETF:QO efficiency might be responsible for the observed MADD‐like phenotype. The patient's clinical picture improved after supplementation of Rf, l‐carnitine, Coenzyme Q10, and also 3OH‐butyrate. This report demonstrates that, even in the absence of genetic defects in genes involved in Rf homeostasis, further targeted molecular analysis may reveal secondary and possibly treatable biochemical alterations in this pattern.In this report, we describe the case of an 11‐year‐old boy, who came to our attention for myalgia and muscle weakness, associated with inappetence and vomiting. Hypertransaminasemia was also noted, with ultrasound evidence of hepatomegaly. Biochemical investigations revealed acylcarnitine and organic acid profiles resembling those seen in MADD, that is, multiple acyl‐CoA dehydrogenase deficiencies (OMIM #231680) a rare inherited disorder of fatty acids, amino acids, and choline metabolism. The patient carried a single pathogenetic variant in the  Secondary and possibly treatable biochemical alterations linked to Rf homeostasis can be revealed by targeted molecular analysis, even in the absence of a genetic defect in the involved genes.1To perform the terminal metabolism of fatty acids and amino acids, several flavin‐dependent oxidoreductases must be functionally active in the mitochondria of tissues with high energy demand, such as muscle. A prominent role in these pathways is played by different acyl‐CoA dehydrogenases (ACADs) involved in the beta‐oxidation of fatty acids: that is, short‐chain (SCAD), medium‐chain (MCAD), long‐chain (LCAD), very‐long‐chain (VLCAD) acyl‐CoA dehydrogenases, and novel members of the same family, that is, ACAD10 and 11. Besides involvement in beta‐oxidation, an additional chaperoning role was recently proposed for ACAD9.ETF and ETFDH are responsible for a rare inborn error of metabolism named multiple acyl‐CoA dehydrogenase deficiency (MADD) or glutaric aciduria of type II (OMIM #231680) characterized by a disorder of fatty acids and certain amino acids metabolism, abnormal acylcarnitine plasmatic profile, and secondary carnitine deficiency. Its clinical presentation is heterogeneous, ranging from a severe, neonatal form, characterized by hypoketotic hypoglycemia, metabolic acidosis, cardiomyopathy, and hepatomegaly with or without congenital anomaliesHomozygous or compound heterozygous mutations in SLC52A1),FLAD1),SLC25A32)SLC52A3)SLC52A2),Recently, mutations in genes involved in Rf transport and metabolism, that is, Rf transporter 1 gene , one member of the ACAD family, which catalyzes the conversion of isobutyryl‐CoA to methacrylyl‐CoA in the third step of valine catabolismHere, we describe a case of an 11‐year‐old boy, who revealed clinical symptoms, acylcarnitine, and organic aciduria profiles resembling late‐onset MADD, harboring a pathological variant in 22.1Informed consent for participation in this study was obtained from the parents of investigated subject and all procedures were performed in agreement with the Declaration of Helsinki. Ethics committee approval was not necessary for the study.2.2Plasma acylcarnitine and amino acid profiles were performed by liquid chromatography (LC)‐MS/MS.2.3Q score (minimum threshold of 30) and visualized by the Integrative Genome Viewer (IGV). Library preparation and exome capture were performed using the Twist Human Core Exome Kit (Twist Bioscience) according to the manufacturer's protocol and sequenced on the Illumina NovaSeq 6000 platform. The BaseSpace pipeline (Illumina) and the TGex software (LifeMap Sciences) were used for variant calling and annotating variants, respectively. Sequencing data were aligned to the hg19 human reference genome. Mutational analysis was focus to a in silico gene panel that includes the coding regions and splice junctions of genes associated to biochemical phenotype: ETFA (NM_000126), ETFB (NM_001985), ETFDH (NM_004453), ACAD8 (NM_014384), ACADS (NM_000017), SLC52A1 (NM_005984), SLC52A2 (NM_001253816), SLC52A3 (NM_033409), FLAD1 (NM_025207), SLC25A32 (NM_030780). Based on the guidelines of the American College of Medical Genetics and Genomics  and visualized by the IGV.Next‐generation sequencing was conducted on DNA extracted from blood leukocytes using standard procedures. Twist Human Core Exome Kit (Twist Bioscience) according to the manufacturer's protocol and sequenced on the Illumina NovaSeq 6000 platform. The BaseSpace pipeline (Illumina) and the TGex software (LifeMap Sciences) were used for variant calling and annotating variants, respectively. Sequencing data were aligned to the hg19 human reference genome. The functional impact of variants was analyzed by Combined Annotation Dependent Depletion V.1.3, Sorting Intolerant from Tolerant (SIFT), and Polymorphism Phenotyping v2 (PolyPhen‐2). Rare variants with minor allele frequency <0.1% were filtered based on the Genome Aggregation Database. Based on the guidelines of the American College of Medical Genetics and Genomics ACMG, S121, a mi2.4Blood samples were collected into evacuated tubes containing K3EDTA. The plasma and packed red blood cells were separated essentially as in the study by Habif et al.g for 10 min and the supernatant was discharged. The washed red blood cells were then osmotically lysed by adding four volumes of lysis buffer , on ice for 5 min, and then centrifuged at 5000 × g for 10 min. The supernatant (hemolysate) was used for enzymatic assays and hemoglobin content measurements, essentially as in the study by Bhaskaram et al.Aliquots (100–200 μl) of packed red blood cells were washed three times with one volume of 9.0 g/L NaCl, centrifuged at 3500 × 2.5For flavin content analysis, 120 μl of either fresh or defrozen plasma were added with 2 mM NaF (as phosphatase inhibitor) and then deproteinized by treatment with 10% perchloric acid as described in the studies by Giancaspero and colleagues.2.6in vitro addition of FAD to hemolysates and it is a good indicator of the nutritional Rf status. Our measurements were carried out essentially as in the studies by Habif and colleagues,Glutathione reductase  is an important flavoenzyme, which in erythrocytes catalyzes the reduction of oxidized glutathione (GSSG) in the presence of NADPH. Erythrocytes GR activation coefficient (EGRAC) represents the degree of stimulation of the endogenous reaction rate resulting from the 2.7Enriched‐membrane erythrocyte fractions (deriving from 100–200 μl cells) were dissolved in sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) loading buffer and separated on 10% T polyacrylamide gels, according to Laemmli.2.8t‐test was used for the comparison of means between patients and controls.All the results were reported as mean ± SEM. Student's 33.1The patient was an 11‐year‐old boy who came for the first time to our attention, for muscle pain and weakness, associated with inappetence and vomiting. Hypertransaminasemia , with echographic evidence of hepatomegaly, was the reason for admission to our division.The second son of two siblings, his parents were healthy and unrelated. He was born at full term from spontaneous delivery, bodyweight 3290 g, and good extrauterine adaptation. He was breastfed until 3 years of age, and psychomotor development and stature‐weight trend were reported to be normal. Episodes of asthma were reported in the first years of life. The patient was first hospitalized at the age of 1 year for hypertransaminasemia and anemia, no further investigations were performed at that time. Two other hospitalizations, at age 4 and 5 years were due to the onset of wheezing and/or asthma exacerbation.Since the age of 6 years, he began to manifest episodes of muscle cramps in apyrexia , easy fatigue, and muscle pains after light exercise. These episodes were sometimes accompanied by vomiting. In the last episode, he came to our attention; a decrease in free carnitine and a significant increase in acylcarnitines from short to very long‐chain was found, together with glutaric and 2‐ketoglutaric aciduria, but also ethylmalonic and dicarboxylic aciduria (Table l‐carnitine (100 mg/kg), with gradual clinical recovery. He performed an in‐hospital trial with Rf (150 mg/day), with normalization of the glutaric aciduria, but persistent abnormality of the other organic acids and acylcarnitines.Over the admission, he underwent an i.v. infusion of glucose 10% (4 mg/kg/min) and l‐carnitine administration was continued per os , together with Coenzyme Q10 (CoQ10). However, given the lack of biochemical response to the test  and the result of genetic analysis, Rf therapy was discontinued  and in the attempt to bypass the possible disturbing ketogenesis, we decided to introduce 3OH‐butyrate into therapy and maintain a higher dose of Rf. After 1 month of the above therapy, laboratory tests revealed normal muscle enzymes and ammonia levels. No significant changes in acylcarnitine profile, compared to the previous assessment, and significant dicarboxylic aciduria were detected  in the ETFDH gene, which is however expected not to be responsible per se of the biochemical altered phenotype.https://www.ncbi.nlm.nih.gov/snp/rs121964955). It has been classified as pathogenic in ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/variation/31576/). Indeed, it is predicted to be probably damaging and tolerated in silico by both PolyPhen‐2 and SIFT, respectively. For ETFDH gene exons and flanking intronic region ±10 bp, but not deep intronic regions have been analyzed.To evaluate our first hypothesis of MADD we performed molecular analyses for SLC52A1, SLC52A2, SLC52A3, SLC25A32, and FLAD1 genes, in which no mutation was revealed.Rf transport and metabolism genes have been recently associated with MADD, thus, our genetic studies included sequencing of ACADS, which codes for SCAD (EC 1.3.8.1) did not reveal any mutations.DNA sequencing of ACAD8 gene, located on chromosome 11q25. These mutations, c.512C>G (p.Ser171Cys) and c.822C>A (p.Asn274Lys), affect the exons 5 and 7, respectively  and one mutation in the ACAD8 gene (c.822C>A). The mother carried the ACAD8 mutation c.512C>G . This variant is seen 3590 times including 40 times in the homozygous state (https://gnomad.broadinstitute.org/variant/11‐134128923‐C‐G?dataset=gnomad_r2_1). It has been reported in the literature in a patient with a compound heterozygous variant.https://www.ncbi.nlm.nih.gov/clinvar/variation/95589/). The Ser171 residue is highly conserved across species, it is positioned between beta‐strands 1 and 2in silico by both PolyPhen‐2 and SIFT.The c.512C>G (p.Ser171Cys) variant is listed as rs113488591 in dbSNP database (https://www.ncbi.nlm.nih.gov/snp/rs371156848). This variant is seen eight times only in a heterozygous state (https://gnomad.broadinstitute.org/variant/11‐134131054‐C‐A?dataset=gnomad_r2_1). Interestingly this mutation has not yet been reported in patients, therefore the phenotypical effects are still unknown. Since the available evidence is currently insufficient to determine the role of this variant in disease, it has been classified as a Variant of Uncertain Significance in ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/variation/1001998/). In the protein, the Asn274 residue is highly conserved across species, and a moderate physicochemical difference occurs in Asn to Lys substitution. The Asn274 residue is positioned in alfa helix G,in silico by both PolyPhen‐2 and SIFT. Similar predictions derive from advanced modeling of protein sequence and biophysical properties reported by Invitae .The c.822C>A (p.Asn274Lys) variant is listed as rs371156848 in dbSNP database  did not reveal any pathogenic variants, we investigated the Rf status in the patient and controls, by evaluating both plasma vitamin/vitamin‐derivative concentrations by HPLC, and FAD abundance through erythrocyte glutathione reductase (EGR) enzymatic assays.Despite mutational analysis of Rf homeostasis connected genes (1stDadm), a significant decrease of both FAD and FMN levels is found compared to controls; a slight, even if not significant, decrease in Rf level is also observed. At the second decompensation (P 2ndDadm), following treatment with CoQ10 and l‐carnitine, FAD values appear to come back to normality. FMN and Rf increased, but they still do not reach the normality. At the start of Rf treatment during the second hospitalization, Rf, but not FMN level, increases, entering the normal interval. Following continuous treatment with Rf, an excess of the vitamin can be observed in the plasma (eight times more than at the first admission). FAD content remains stable and in the normal range, as well as FMN value appeared to be compensated.Table The spectrophotometric enzymatic assay, introduced as EGRAC, is based on the ability of externally added FAD to reactivate the apo‐enzyme, present in erythrocyte ghosts in case of ipo‐vitaminosis . Different from analytic methods, this approach refers to a medium‐term analysis of the nutritional status of Rf,As reported in Table Both analytical and enzymatic results demonstrate a profound alteration of Rf homeostasis in this patient at the first decompensation and a reversal of this biochemical phenotype in response to first treatments and, even better, to high and continuous supplementation with Rf. As far as genetical analysis revealed, Rf homeostasis defects are not congenital, but probably due to a dietary deficiency. Nevertheless, we cannot exclude a secondary defect that may be related to oxidative metabolic stress.3.4To further substantiate Rf homeostasis impairment, the effort was done, as far as we know for the first time, to measure the levels of Rf transporters (RFVT1–3) in membrane‐enriched fractions from erythrocytes by Western blotting. The protein amounts detectable in this way are expected to be the result between the rate of protein expression in erythroblasts and the rate of protein turnover during erythrocyte life.SLC52A1–3, revealed the sole presence of RFVT2  were introduced in Italy by Law , therefore the diagnosis was possible only after clinical manifestations.ETFDH exon 5, which, however, is expected not to be responsible per se for the biochemical altered phenotype.ETFDH heterozygosity to possibly explain this complex phenotype. Quite interestingly, we found compound heterozygous mutations (being the variant c.822C>A never described before) in one member of the ACAD family, that is, the ACAD8 gene, which is potentially responsible for IBDD.In this boy during the metabolic crisis, organic acids and acylcarnitine profile resembling late‐onset MADD led us to suspect mutations in one of the genes currently associated with this pathology, that are linked either to defects in FAD reoxidation (ETF/ETF:QO system) or defects in FAD synthesis/transport. Genetic analysis, indeed, revealed the presence of a single mutation in ACAD8 gene codes for the tetrameric mitochondrial located enzyme, IBD, principally involved in valine metabolism. Like other ACADs, it is expected to directly interact with the “funnel” of electrons, that is, the ETF/ETF:QO system on the internal face of the inner mitochondrial membrane  supplementation. In the attempt to bypass liver beta‐oxidation defects and to ameliorate energetic supply to extra‐hepatic tissue, a nutritional therapy based on low intake of long‐chain lipids and 3OH‐butyrate supplementation was recently introduced, as suggested by Mereis et al.,Fortunately, patient symptoms were successfully treatable with continuous Rf  and with the Helsinki Declaration of 1975, as revised in 2000. Informed consent was obtained from the patient for being included in the study.Appendix S1 Supporting InformationClick here for additional data file.FIGURE S1 Schematic representation of mitochondrial valine metabolism. On the right, mitochondrial valine oxidation pathway and the enzymes involved. On the left, a magnification of the proposed physical interaction between IBD and ETF/ETF:QO system. Names of enzymes are indicated in the figure as listed below: transaminase (EC 2.6.1._); BCKAD: branched‐chain‐2‐oxoacid decarboxylase (EC 4.1.1.72); IBD (ACAD8): isobutyryl‐CoA dehydrogenase (EC 1.3.8._); ETF:QO: electron transfer flavoprotein ubiquinone oxidoreductase (EC 1.5.5.1); ETF: electron transfer flavoprotein; crotonase (EC 4.2.1.17); HIBCH: 3‐hydroxyisobutyryl‐CoA hydrolase (EC 3.1.2.4); HIBADH: 3‐hydroxyisobutyrate dehydrogenase (EC 1.1.1.31); MMSDH: methylmalonate‐semialdehyde dehydrogenase (EC 1.2.1.27).Click here for additional data file.ACAD8 gene and in IBD protein.FIGURE S2 Localization of mutations in  (a) Schematic representation of ACAD8 gene structure with exons (boxes E1‐E11) and introns (lines between boxes) showing the localization of the investigated gene variations . (b) Structure of isobutyryl‐CoA dehydrogenase: ribbon representation of isobutyryl‐CoA dehydrogenase protein based on the crystal structure of human IBD (PDB ID: 1RX0).32 In the insets, zoom into the IBD chain A, showing Ser171Cys (c) and Asn274Lys (d) natural mutations.Click here for additional data file.


A growing number of studies support a bidirectional relationship between inflammation and bipolar disorders. Tumor necrosis factor‐α (TNF‐α) inhibitors have recently attracted interest as potential therapeutic compounds for treating depressive symptoms, but the risk for triggering mood switches in patients with or without bipolar disorders remains controversial. Thus, we conducted a systematic review to study the anti‐TNF‐α medication‐induced manic or hypomanic episodes. PubMed, Scopus, Medline, and Embase databases were screened for a comprehensive literature search from inception until November 2020, using The Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines. Out of the initial 75 references, the screening resulted in the inclusion of four case reports (each describing one patient) and a cohort study (in which 40 patients out of 7600–0.53% – experienced elated mood episodes after infliximab administration). Of these 44 patients, 97.7% experienced a manic episode and 2.3% hypomania. 93.2% of patients had no history of psychiatric disorder or psychotropic treatment. Only 6.8% had a history of psychiatric disorders with the affective spectrum (4.6% dysthymia and 2.3% bipolar disorder). The time of onset of manic or hypomanic symptoms varied across TNF‐α inhibitors with an early onset for Infliximab and a later onset for Adalimumab and Etanercept. These findings suggest that medications targeting the TNF‐α pathway may trigger a manic episode in patients with or without affective disorders. However, prospective studies are needed to evaluate the relative risk of such side effects and identify the population susceptible to secondary mania. A growing number of studies supports a bidirectional relationship between inflammation and bipolar disorders (BDs)Moreover, lithium therapy – the mainstay treatment for BDs treatment – yields immunomodulatory effectsGiven the case for the role of inflammation and innate immunity in BDs pathophysiology, molecules targeting the TNF‐α pathway have recently attracted interest as potential therapeutic compounds. Disease‐modifying antirheumatic drugs (DMARDs), including TNF‐α inhibitors , have shown positive effects on the affective, cognitive, and somatic function of patients with inflammatory illnesses.https://osf.io/mt7jb/quickfiles) and adhered to the procedures of Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) statementThis systematic review followed a pre‐defined protocol available online  reported the use of TNF‐α inhibitors in patients with or without mood disorders according to the Diagnostic and Statistical Manual (DSM) or the International Classification of Diseases (ICD); (ii) a qualitative measure of manic or hypomanic episodes induced by TNF‐α inhibitors as side effects; (iii) were written in English. Commentaries, editorials, and reviews were excluded. All articles published until November 2020 were included, while no publication status restrictions were imposed.Every reference was screened by at least two researchers independently (A.M. and V.D.P.), any disagreement was discussed between the two, and whenever it was not possible to make a decision, a third researcher was involved in the discussion (F.S.). Once the full‐text articles were selected, the data retrieved have been entered into a spreadsheet. Sample size, demographics, previous treatment, treatment response, adverse effects, and follow‐up time were extracted. The analysis of the data was made by comparison. The heterogeneity of the results, such as the type of studies identified, did not allow us to perform a meta‐analysis. A narrative synthesis was considered the best approach to describe and analyze the results.The database search, after duplicates removal, brought a total of 71 records. Following the inclusion/exclusion criteria, the screening resulted in the inclusion of 5 full‐text articles Fig. 24. The To our knowledge, this is the first systematic review conducted to date assessing the available evidence about the role of TNF‐α antagonists in inducing secondary manic episodes or exacerbating a mood switch in patients with or without mood disorders.Hitherto, a cohort study,TNF‐α antagonists had recently attracted interest as potential therapeutic compounds for mood disorders.A recent systematic review and meta‐analysis finally confirmed altered peripheral markers in BD, according to which IL‐6 seems to be a trait marker for BDs, while CRP and TNF‐α could constitute state markers, as they are increased during mood episodes,Increased cytokine variability suggests that a subset but not all patients may exhibit cytokine elevations as part of a manic episode.TNF‐α is a major Th1‐class pro‐inflammatory cytokine, that can bind to TNFR1 and/or TNFR2, activating downstream signaling pathways that mediate a wide variety of biological responses, including apoptosis, cell differentiation, proliferation, survival, homeostatic synaptic plasticity and inflammationvia the tumor necrosis factor‐α pathway that are crucial factors in the pathogenesis of BDs.TNF‐α contributes to brain development, particularly by modulating hippocampal growth and function.et al. assessed infliximab safety and efficacy for patients with treatment‐resistant unipolar and bipolar depression. Although the overall antidepressant effect was negative, a significant antidepressant effect was observed in the subgroup with elevated serum C reactive protein levels.From the therapeutic point of view, given the role of the interaction between the Serotonin/Norepineprhin system and Th1/Th2 immune response balance,Some limitations to this systematic review have to be acknowledged. First, the available evidence is limited to four case reports and a cohort study, all characterized by small sample sizes. Second, given the lack of prospective evidence, we cannot draw firm conclusions on causality. Third, the population who experienced secondary mania is heterogeneous both in terms of diagnosis and treatment.In conclusion, these psychiatric adverse events' characterization is essential for adequately assessing the risk–benefit ratio and improving the management of these events when they occur. Prospective studies with a multidisciplinary approach, close psychiatric monitoring, and serial cytokine levels measures are warranted to demonstrate the relative risk of secondary mania after TNF‐α inhibitors administration, or abrupt discontinuation (as seldom reported for SSRIsThe authors declare no conflict of interest.A.M., V.D.P., and F.S. conducted the literature review. F.S., G.P., and M.S. guided the areas for discussion. A.M., V.D.P., N.M., and F.S. conducted the statistical analysis. A.M., V.D.P., and N.M. wrote the draft of the manuscript. All authors have equally contributed to the critical revision of the manuscript.The authors received no specific funding for this work.Appendix S1. Supporting information.Click here for additional data file.


Duodenal‐type follicular lymphoma (FL) is a rare and newly recognized disease. Few data are available on the outcomes and treatment strategies for patients with duodenal‐type FL. We aimed to investigate the clinical features and outcomes of duodenal‐type FL. We defined duodenal‐type FL as involvement of the duodenum, without nodal or extranodal lesions other than intestinal lesions, pathologically diagnosed as FL. We reviewed 26 patients with duodenal‐type FL between January 2011 and December 2020 at Kobe City Hospital Organization, Kobe City Medical Center General Hospital. In particular, patients were selected for the watch and wait (WW) strategy and followed up with regular esophagogastroduodenoscopy about once a year at our institution. The patient characteristics were as follows: median age 63.5 years (range: 42–78), sex , stage , and grade . Regarding treatment strategies, 23 patients were selected for the WW strategy, and three patients received initial rituximab therapy. The median follow‐up period was 65.5 months (range: 0.2–109). Five‐year progression‐free survival and 5‐year overall survival rates were 86.3% and 100%, respectively. Among the 23 patients selected for the WW strategy, six had spontaneous complete regression, and 14 had stable disease, and three had progressive disease, including one with histologic transformation. The WW strategy for patients with duodenal‐type FL could be an appropriate and safe treatment option. However, in several cases, disease progression was documented, and regular follow‐up is important. FL commDuodenal‐type FL (DFL), which was recognized in the 2017 World Health Organization classification, is a rare and specific variant of FL that is predominantly involved in the second portion of the duodenum . In geneTherefore, we followed up patients with DFL with regular esophagogastroduodenoscopy (EGD) about once a year and aimed to investigate the clinical features and outcomes of DFL.22.1In this study, we defined DFL as involvement of the duodenum, without nodal or extranodal lesions other than intestinal lesions, pathologically diagnosed as FL.n = 9); and (ii) unavailable EGD data on initial examination (n = 1). The remaining 26 patients were included in the study.We retrospectively identified 350 patients with newly diagnosed FL at our institution between January 2011 and December 2020. We found that 36 patients with FL had duodenal involvement. Among them, a total of 10 patients were excluded for the following reasons: (i) nodal or extranodal lesions other than intestinal lesions . The requirement for written informed consent was waived as this study used retrospective data obtained from hospital records, and there were no interventions in the study patients.2.2The diagnostic work‐up and staging procedures on presentation included inquiry of patient's medical history and complete physical examination, chest radiography, whole‐body computed tomography (CT) scanning, and/or (18)F‐fluorodeoxyglucose positron emission tomography/CT ((18)F‐FDG PET/CT), and bone marrow examination. The clinical staging of each patient was determined according to the Lugano classification of gastrointestinal lymphoma . In most2.3At the time of diagnosis of DFL, complaining of gastrointestinal symptoms regardless of their degree was defined as symptomatic. In patients who received initial treatment, assessment of response was determined according to the Lugano classification . In pati2.4All variables shown in the table and the figures were retrospectively obtained from the patient records. Continuous variables were summarized using medians with interquartile ranges (quartiles 1–3), and categorical variables were summarized as counts and percentages. Event rates of OS and PFS were estimated using the Kaplan–Meier method with a 95% confidence interval. All statistical analyses were performed using EZR  .3n = 3), and abdominal discomfort (n = 3). Findings of EGD revealed macroscopic characteristics and locations as follows: 21 (81%) multiple whitish small polyps , three (11%) flat‐elevated lesion (only second portion [n = 3]), one (4%) semicircumferential redness (only second portion [n = 1]), and one (4%) depressed superficial lesion (only second portion [n = 1]) in the duodenum (Table The patient characteristics at diagnosis are summarized in Table Over the median follow‐up period of 65.5 months range: 0.2–109), 5‐year PFS was 86.3% , and 5‐year OS was 100%  with reappearance of duodenal lesion was selected for the WW strategy because of the low tumor burden and subsequently achieved sCR.4DFL is a rare and newly recognized disease . There iThe prognosis of DFL is excellent. The largest retrospective study of DFL enrolled 125 patients with primary gastrointestinal FL, including 101 (89%) patients with duodenal involvement, in which more than half of the patients were treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R‐CHOP) or R‐CHOP‐like regimen or rituximab monotherapy and revealed that 5‐year PFS and 5‐year OS were 93% and 100%, respectively . AnotherSince most studies on DFL are retrospective, no definite recommendations in terms of optimal treatment can be extrapolated , 14, 15.From another perspective, some cases achieved sCR with the WW strategy , 13. In In contrast, although relatively rare, patients with DFL have a risk of progression (<10%) and HT 3.8%) , 8. Prog% , 8. PrOur study has several limitations. First, there may be a bias of treatment selection and no definite treatment recommendations can be extrapolated because of the retrospective nature of this study. Second, the number of patients with DFL was small, and the treatment strategies were not compared. Third, we distinguished between FL and DFL by localization, not pathologically or genetically, which may be insufficient.In conclusion, our study showed a very indolent clinical course and a good prognosis of DFL. The WW strategy for patients with DFL could be an appropriate and safe treatment option. However, in several cases, disease progression was documented, and regular follow‐up is important.The authors declare no conflict of interest.


The therapeutic strategy for the treatment of known sequelae of COVID‐19 has shifted from reactive to preventative. In this study, we aim to evaluate the effects of acetylsalicylic acid (ASA), and anticoagulants on COVID‐19 related morbidity and mortality.n = 206) and inpatient (n = 333) cases from three management protocols, including standard care (SC) (n = 399), low‐dose ASA only (ASA) (n = 112), and anticoagulation only (AC) (n = 28). Collected data included demographics, comorbidities, and clinical outcomes. The primary outcome measure was inpatient admission. Exploratory secondary outcome measures included length of stay, 30‐day readmission rates, medical intensive care unit (MICU) admission, need for mechanical ventilation, the occurrence of acute respiratory distress syndrome (ARDS), bleeding events, clotting events, and mortality. The collected data were coded and analyzed using standard tests.This record‐based analytical cross‐sectional study targeted 539 COVID‐19 patients in a single United States medical center between March and December 2020. Through a random stratified sample, we recruited outpatient (p = 0.63), MICU admission , ARDS , and death .Age, mean number of comorbidities, and all individual comorbidities except for asthma, and malignancy were significantly lower in the SC compared to ASA and AC. After adjusting for age and comorbidity via binary logistic regression models, no statistical differences were found between groups for the studied outcomes. When compared to the SC group, ASA had lower 30‐day readmission rates (odds ration [OR] 0.81 95% confidence interval [CI] 0.35–1.88, Low‐dose ASA has a nonsignificant but potentially protective role in reducing the risk of COVID‐19 related morbidity and mortality. Our data suggests a trend toward reduced 30‐day readmission rates, ARDS, MICU admissions, need for mechanical ventilation, and mortality compared to the standard management protocol. Further randomized control trials are needed to establish causal effects. ACanticoagulation only groupANOVAanalysis of varianceARDSacute respiratory distress syndromeASAacetylsalicylic acid, ASA only groupCIconfidence intervalCNScerebrovascular diseaseCOPDchronic obstructive pulmonary diseaseCVDcardiovascular diseaseDMdiabetes mellitusHRhazard ratioHTNhhypertensionIRBinstitutional review boardISTHInternational Society on Thrombosis and HemostasisLOSlength of stayMICUmedical intensive care unitORodds ratioSARS‐CoV‐2severe acute respiratory distress syndrome coronavirus‐2SCstandard care groupSDstandard deviationsSPSSStatistical Package Software Statistics1Coronavirus disease 2019 (COVID‐19) is a novel respiratory disease caused by the severe acute respiratory syndrome coronavirus (SARS‐CoV‐2). In the United States, there have been over 32 million cases and 580,000 deaths from the virus as of May 2021.Current guidelines for managing outpatients with COVID‐19 include mostly supportive care. Of note, there is no current guideline recommending low‐dose acetylsalicylic acid (ASA) for prehospital COVID‐19 patient.A recent study showed that patients with COVID‐19 who received low‐dose ASA were associated with a lower incidence of requiring mechanical ventilation, ICU admission, and in‐hospital mortality.2This record‐based analytical cross‐sectional study collected a stratified random sample of 539 patients from a total of 2714 available confirmed COVID‐19 patients at a single upstate New York, USA medical center between March 1, 2020, and December 1, 2020. Patient information was collected from both the inpatient and outpatient settings.The criteria for inclusion into the study included all confirmed COVID‐19 cases that were identified by a positive result of real‐time polymerase‐chain‐reaction, aged 18–89 years old, and exclusion criteria included: current pregnancy, current clopidogrel use, current incarceration, a prior history of thromboembolism or hereditary hypercoagulable disorder, and surgery or hospitalization for reasons other than COVID‐19‐related illness during or 14 days before the indexing period.2.1n = Z2) P (1 − P)/d2. From the total number of 2714 potentially relevant cases, Based on the reported cases at the study setting between March 1, 2020, and December 1, 2020, and based on the prevalence of our primary outcome (inpatient admission) in the United States, hospitalizations due to COVID‐19 accounted for 14% of reported cases,n = 399) (74.0%), ASA only (ASA) (n = 112) (20.8%), and anticoagulation only (AC) (n = 28) (5.2%) with the associated percentage of total patients being outpatient (n = 206) (37.8%) and inpatient (n = 333) (62.2%). Patients who reached inpatient care through hospital admission were not counted in the outpatient group.The sample size was estimated according to the following equation:  or taking any anticoagulation agents during the indexing period were excluded from this group.Groups were defined as:All groups were treated with the same basic management protocol based on guidelines by Upstate University Hospital.2.2Medication history was used to identify patients taking ASA and other anticoagulants. Inpatient admission was defined as a hospital stay of at least 24 h. Respiratory data collected included the presence of acute respiratory distress syndrome (ARDS) defined by the Berlin criteria, the need for mechanical ventilation, and total intubation time until extubation or death. Bleeding events were defined by International Society on Thrombosis and Hemostasis criteria as clinically overt bleeding accompanied by a decrease in the Hb level of ≥2 g/dl or transfusion of ≥2 units of packed red cells, occurring at a critical site, or resulting in death. These events included gastrointestinal bleeding, intracranial bleeding, and any bleeding that required surgical or interventional radiology intervention. Clotting events included deep venous thrombosis, pulmonary embolism, and peripheral arterial occlusion occurring during the hospitalization. Mortality was defined as death occurring following the diagnosis of an acute COVID‐19 infection.Information obtained from patient records included demographic data, comorbidities, clinical outcome data (primary and secondary as listed below in study objectives), and mortality. 2.3The objective of this study was to study the effects of ASA and anticoagulants on COVID‐19‐related outcomes. The primary outcome measure in this study was inpatient hospital admission. Additionally, exploratory methods were used to evaluate secondary outcomes including length of hospital stay, 30‐day readmission rates, medical intensive care unit (MICU) admission, need for mechanical ventilation, the occurrence of ARDS, bleeding events, clotting events, and mortality.2.4f) and percentage (%); χ2 was used for the analysis of these variable. Mean, standard deviation (SD), two‐sided independent t‐test, and two‐sided analysis of variance (ANOVA) test were used for quantitative, normally distributed data summarization, and analysis. While median, Interquartile range, and two‐sided Kruskal–Wallis tests were used for summarization, and analysis of nonparametric quantitative variables. p value is the probability of finding the observed or more extreme results when the null hypothesis is true and considered significant when p < 0.05; the 95% confidence interval (CI) will contain the true parameter value. 95% of the time, a study has to be repeated many times using different samples.The collected data were coded and analyzed using Statistical Package Software Statistics (SPSS) version 26.0 (IBM Corp.). Qualitative data summarization was prepared using frequency  values were rounded to 1.1, which means no correlation between a given predictor variable and any other predictor variables in the model , Omnibus test model χ2, Cox and Snell R2, Nagelkerke R2, and overall percentage.The following tests were used to predict COVID‐19 outcomes, including primary outcomes (inpatient admissions) and exploratory secondary outcomes  through the following tests: Hosmer and Lemeshhow test, 3p < 0.001). There was no statistically significant difference between sex, asthma, or malignancy. Diabetes mellitus (n = 35) (47.3%), and dyslipidemia (n = 78) (69.6%) were the most frequent comorbidities observed among patients in the ASA group. While cardiovascular disease n = 19 (67.0%), OSA (n = 10) (35.7%), and COPD (n = 9) (32.1%) were most frequent among patients in the AC group  and comorbidities  and total number of comorbidities between the SC group and other groups (ASA and AC). Patients on ASA, and AC were significantly older, had higher body mass index's (BMI), and a greater number of comorbidities than patients in the SC group ((n = 9) 3.1% were p < 0.05) including inpatient admission, bleeding events, and death with the exception of clotting events. Patients in the AC group followed by the ASA group had statistically higher rates of inpatient admission when compared to the SC group , bleeding events , and death  , ASA n = 25 (12.1%), and AC n = 5 (2.4%). There was a statistically significant difference (p < 0.05) between the SC group and other groups regarding the groups: age, number of comorbidities, and comorbidities except for asthma, and malignancy. The SC group was significantly younger and had a lower median number of comorbidities compared to the ASA and AC groups . A large proportion of the outpatient SC group did not have any of the studied comorbidities (n = 57 [32.4%]), a statistically significant difference from the AC and ASA groups (n = 0 [0%] and n = 1 [4%])  were inpatient portion of this study. These were distributed into the following: SC n = 223 (66.9%), ASA n = 87 (26.1%), and AC n = 23 (6.9%). There was a statistically significant difference (p < 0.05) between the SC group and other groups regarding age, mean number of comorbidities, and comorbidities except for asthma, and malignancy. Again, the SC group was significantly younger with fewer comorbidities than the other groups. All studied primary and secondary outcomes did not show statistically significant differences except for mean length of stay (LOS), which was significantly longer in the AC when compared to SC and ASA  (Table There were 333 patients identified for the COVID‐19 p = 0.32). AC trended toward increased OR when compared to SC for almost all categories, but again did not reach statistical significance, most notably 30‐day readmission rates . MICU admission in this group was noted to be at decreased risk   between the SC group and other groups regarding age, mean number of comorbidities, and all individual comorbidities except for asthma, and malignancy. This finding is related to the indication for ASA and therapeutic AC use in the ASA and AC groups, respectively. In the studied population, ASA was primarily used for secondary prevention of thromboembolic diseases such as coronary artery disease, cerebrovascular disease, and peripheral vascular disease. As a result, the ASA and AC groups contained patients with a much higher number of comorbidities, than the SC group. Patients on ASA tend to have more risk factors for severe COVID‐19 infection  and thus generally have worse outcomes.In this study, the randomly selected patients were distributed into the three management protocols, in which the majority of COVID‐19 cases were managed with the SC protocol (74%), and the remaining were managed with prophylactic AC and ASA (20.8%), and therapeutic anticoagulation (5.2%). Due to this distribution, more than 80% of COVID‐19 cases had mild symptoms, with critical cases being less than 10%.The duration of hospital stay (days) was significantly higher in the AC group (median 12 days) compared to other groups. Moreover, the odds of secondary outcomes, including 30‐day readmission, the occurrence of ARDS, ICU admission, and mortality were also higher in the AC group. This result is in agreement with recent literature, most notably a recent study by Sadeghipour et al., who concluded that routine use of intermediate‐dose anticoagulation did not decrease the severity of COVID‐19 and had no mortality benefit.p = 0.045), further supporting the role of ASA in COVID‐19.ASA reduced 30‐day readmission rates, the occurrence of ARDS, ICU admissions, and mortality. We hypothesize that this effect is due to ASA's anti‐inflammatory effect, antiplatelet aggregation, pleiotropic effects, and potential antiviral effect.Among the inpatient COVID‐19 studied cases, there was no statistically significant difference regarding clinical outcomes between the studied groups, which is similar to results reported by Chow et al. and Yuan et al.p = 0.38) when compared to SC. This is in agreement with Zhou et al. who proposed that low‐dose ASA administration before hospitalization can prevent severe ARDS in COVID‐19 and decrease the risk of serious complications.Low‐dose ASA was shown to reduce the risk of ARDS  when compared to the SC group. Our data are similar to other studies that found a nonsignificant reduction in mortality.Low‐dose ASA decreased the risk of mortality among COVID‐19 cases in the multivariate analysis .The main strengths of our study were that the relatively large sample size was collected over the long duration of the pandemic, from March until December, and the many outcomes were studied in detail. Every case fulfilling the selection criteria has an equal chance of being recruited into the sample (so it is a random sample) to find the association and risk assessment.5Low‐dose ASA is a promising, effective, protective medication in potentially improving the outcomes in COVID‐19 cases, through reducing mortality, and morbidity  but not statistically significant due to the higher risk patients in these groups. further prospective research is still needed.6Further multicenter, prospective, randomized controlled trials with sufficient matching are required to further investigate the role and mechanism of ASA in the management of COVID‐19. We encourage further investigation of easily accessible, common, and safe medications with notable mechanisms of action to aid in the fight against COVID‐19‐related morbidity and mortality.Muhammad B. Malik: Conceptualization; investigation; methodology; project administration; resources; validation; writing—original draft; writing—review and editing. Samar A. Amer: Conceptualization; formal analysis; visualization; writing—original draft; writing—review and editing. Eric Merrell: Conceptualization; investigation; writing—original draft; writing—review and editing. Ronald Russo: Conceptualization. Jeffrey B. Riley: Formal analysis; methodology; resources; validation. Elizabeth James: Investigation. Anderson Anuforo: Investigation. Soumya Adhikari: Investigation. Philip Chebaya: Investigation. Edward Darling: Writing—original draft. Michael Kuhn: Writing—original draft. Gary Nieman: Writing—original draft. Ahmed Shawkat: Conceptualization. Hani Aiash: Conceptualization; methodology; project administration; resources; supervision; validation; writing—review and editing. All authors have read and approved the final version of the manuscript.The authors declare no conflict of interest.I affirm that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned  have been explained.This study was reviewed by the institutional review board (IRB) at Upstate Medical University and was considered exempt according to the #4(iii) exemption category in federal regulations. The requirement for written informed consent was waived by the IRB and the study was conducted in accordance with ethical principles.


There is a universal need to increase the number of adults meeting physical activity (PA) recommendations to help improve health. In recent years, electrically assisted bicycles (e‐bikes) have emerged as a promising method for supporting people to initiate and maintain physical activity levels. To the best of our knowledge, there have been no meta‐analyses conducted to quantify the difference in physiological responses between e‐cycling with electrical assistance, e‐cycling without assistance, conventional cycling, and walking.2), power output (PO), and metabolic equivalents (METs) outcomes were included within the meta‐analysis.A systematic review and meta‐analysis was conducted following PRISMA guidelines. We identified short‐term e‐bike studies, which utilized a crossover design comparing physiological outcomes when e‐cycling with electrical assistance, e‐cycling without electrical assistance, conventional cycling, or walking. Energy expenditure (EE), heart rate (HR), oxygen consumption (VON = 239). E‐cycling with electrical assistance resulted in a lower energy expenditure (EE) , heart rate (HR) , oxygen uptake (VO2) , power output (PO) , and metabolic equivalent (MET) response , compared with conventional cycling. E‐cycling with moderate electrical assistance resulted in a greater HR response , and VO2 response [SMD 0.34  p = 0.16] compared with walking.Fourteen studies met our inclusion criteria (E‐cycling was associated with increased physiological responses that can confer health benefits. As such, studies which measured these physiological responses were included within this systematic review and meta‐analysis. Experimental or observational studies, pre‐ and post‐design, quasi experimental, randomized, and non‐randomized cross‐over trials were included. Only papers written in English were included. Assessment of outcomes was laboratory or field based. Studies with adults, adolescents, and children were included.Inclusion criteria included acute, single ride comparison studies which assessed e‐cycling with assistance compared to e‐cycling without assistance, conventional cycling or walking. Acute e‐bike studies predominantly measure energy expenditure (EE), heart rate (HR), oxygen uptake .Search strategy: Databases searched were PsychINFO, MEDLINE, Embase, ISI Web of Science, CINAHL complete, SPORTDiscuss, Scopus, and PubMed, and were searched from database inception to August 2020. Our full search strategy is available in an additional word document (see Appendix Researchers (JM and MK) independently screened and reviewed titles and abstracts to identify eligible studies. Researchers  assessed full‐text articles for eligibility. Researchers (JM and RD) independently performed data extraction and quality assessment for the studies included within the meta‐analysis. Any discrepancies were discussed with RM.Quality assessment: The quality assessment tool for quantitative studies developed by the Effective Public Health Practice ProjectData extraction: JM and RD extracted data from the papers independently. If papers did not include a full data set, the authors were contacted. Data were extracted using Covidence systematic review software , and discrepancies were discussed between researchers. Data extracted included authors and their institution, methodological design, participant population and characteristics, intervention characteristics, and intervention outcomes. Data were synthesized and presented in table format with narrative description.32 (L/min or ml/kg/min) is reported as SMD. PO is reported as mean difference as all studies reported PO in watts (W). METs are reported as mean difference. Nine studies reported METs, four studies were included within the MET meta‐analysis and are reported as mean difference. All studies which reported METs are described narratively. For comparisons of SMD, the value was reported as units of standard deviation rather than the units reported for the outcome measured. We considered a SMD of 0.2 as a small effect, 0.5 as a moderate effect, and 0.8 as a large effect.Data extracted from the studies were continuous outcomes; therefore, within the meta‐analysis, these data were assessed as either mean difference or standardized mean difference (SMD). EE  data are presented as SMD. HR data are reported as mean difference as all studies included within the meta‐analysis reported HR in beats per minute (BPM). VO4A total of 811 articles were obtained from the initial search and one paper was found through hand searching. After removal of 184 duplicates, 628 studies were title and abstract screened. From the 628 identified, 39 full texts were reviewed. After full‐text review, 14 studies were identified with 12 providing complete data, an additional word document containing the PRISMA flow diagram is available , however, this finding was not significant. Although an increase in EE from baseline was observed during all cycling conditions, the largest difference between conditions was observed between e‐cycling with high electrical assistance and e‐cycling without electrical assistance SMD 2.66 .Overall, EE  increased when e‐cycling with electrical assistance; however, values were lower than any comparator; there was a small decrease in EE for e‐cycling with moderate electrical assistance compared with conventional cycling  BPM compared with conventional cycling. Compared with walking, e‐cycling with electrical assistance was associated with a higher HR ; however, was not significant 2 increased from baseline when e‐cycling with electrical assistance, e‐cycling without assistance, conventional cycling, and walking. VO2 was higher when e‐cycling with electrical assistance compared to walking; however, this finding was not significant . VO2 when e‐cycling with a moderate assistance was lower compared with conventional cycling, SMD −0.57 .VOp = 0.0001) compared with conventional cycling. E‐cycling with high electrical assistance was associated with the largest difference in PO, mean difference −53.71 W .PO during e‐cycling with moderate electrical assistance was lower, mean difference −31.19 W .A small difference is observed between e‐cycling with moderate assistance compared with conventional cycling, −0.83 METs , physiological responses were lower than observed with conventional cycling, or e‐cycling without electrical assistance, but generally greater than that observed when walking. Conventional cycling, e‐cycling without assistance, and walking were used as comparators to allow for a realistic comparison of modes of active transport as conventional cycling and walking are well‐established modes of active travel. E‐cycling without assistance and e‐cycling with high assistance were included as comparators as e‐bikes without assistance are heavier than a conventional bike and people may not continuously e‐cycle with assistance on. Furthermore, people may choose to e‐cycle with a high assistance level.In this systematic review and meta‐analysis, we aimed to quantify the physiological response from e‐cycling with electrical assistance when compared with e‐cycling without electrical assistance, conventional cycling, or walking. Overall, e‐cycling was associated with an increase in physiological responses, equivalent to moderate intensity physical activity. Across a host of physiological parameters , which is required by Cochrane as the minimum for a meta‐analysis; however, more studies with similar outcomes and methodologies would substantiate these findings. Moreover, topography varied between studies which could have an impact on outcomes. Our search criteria excluded non‐English manuscripts meaning studies could have been missed. Reported I2 values infer substantial heterogeneity between various included studies, to combat this, we ran random effects models which could have produced wider CI.To the best of our knowledge, this is the first meta‐analysis to quantify and compare the short‐term physiological effects of e‐cycling with more conventional forms of active transport . We undertook a comprehensive search of short‐term e‐bike studies that assessed physiological responses. This study provides new data on the physiological responses associated with e‐cycling and its potential as a public health initiative for promoting recommended levels of physical activity. A limitation was the lack of data for certain outcome measures. Some results were based on two studies  is an increasing problem globally. Many adults worldwide do not meet recommended guidelines for physical activity levels and therefore public health strategies are urgently needed to help people engage in regular physical activity. Research has shown that electric bikes, which provide electrical assistance while cycling may offer an ideal approach for increasing physical activity levels, particularly for those who have difficulty exercising. However, little is known about the short‐term physiological effects of electric assisted cycling (e‐cycling) and how it compares with conventional cycling. Results from this meta‐analysis showed that e‐cycling was comparable with moderate intensity physical activity, which offer health benefits. Randomized controlled trials are warranted to test this. In summary, e‐cycling offers a viable approach to support people to be more physically active. Healthcare professionals might consider encouraging e‐cycling when providing options to support people to be physically active. Moreover, government policies and public health initiatives such as subsidy of electric bikes may facilitate greater uptake.13E‐cycling was associated with an increase in physiological response that can confer health benefits. The magnitude of effect in physiological responses was lower than compared with conventional cycling. Nonetheless, e‐cycling is of sufficient intensity to meet PA recommendations. Compared with walking, e‐cycling with electrical assistance offered greater physiological response. For many people, e‐cycling offers an ideal entry approach for promotion of physical activity.The authors declare that they have no conflict of interest.JM and MK independently screened and reviewed titles and abstracts to identify eligible studies. JM, AB, and LP assessed full‐text articles for eligibility. JM and RD independently performed data extraction and quality assessment for the studies included within the meta‐analysis. JM conducted meta‐analysis. Any discrepancies faced throughout the development of the manuscript were discussed with RM. All authors contributed to the writing of manuscript. All authors read and approved final manuscript.Appendix S1Click here for additional data file.Appendix S2Click here for additional data file.Appendix S3Click here for additional data file.Appendix S4Click here for additional data file.