Diffusion tensor imaging in euthymic bipolar disorder - A tract-based spatial statistics study.
BACKGROUND
In the current DTI study we compared euthymic bipolar I disorder (BD-I) patients and healthy controls (HC). We subsequently divided the total patient group into lithium-users and non-lithium-users and estimated differences across the three groups.


METHODS
Twenty-one euthymic BD-I patients and twenty-two HC participants were included in psychiatric interviews and MRI image acquisition (diffusion-weighted (DW) and T1-weighted scans). Fractional anisotropy (FA), radial, mean and axial diffusivity (RD, MD, AD) were estimated from the DW data, using DTI. These measures were then compared between groups using FSL Tract Based Spatial Statistics (TBSS). Correlations with age at onset, number of episodes and depression score were analyzed.


RESULTS
A difference in FA, MD, RD and AD between the whole sample of euthymic BD-I patients and healthy controls could not be detected. Amongst others, lithium-using patients demonstrated a higher FA and lower RD when compared to non-lithium-using BD-I patients in the corpus callosum and left anterior corona radiata. Widespread clusters demonstrated negative FA associations and positive RD and MD associations with minor depressive symptoms.


LIMITATIONS
Patients were naturalistically treated. Although the sample size is comparable to several other DTI studies, a larger sample size would have been benificial. TBSS and DTI have their own limitations.


CONCLUSION
Our findings support the theory that previously described DTI-based microstructural differences between HC and BD patients could be less pronounced in euthymic BD patients. Differences in FA between patients using and not using lithium suggest a counteracting effect of lithium on white matter microstructural disturbances.
["Haarman|Bartholomeus C M 'Benno'|BCM'|", 'Riemersma-Van der Lek|Rixt F|RF|', 'Burger|Huibert|H|', 'de Groot|Jan Cees|JC|', 'Drexhage|Hemmo A|HA|', 'Nolen|Willem A|WA|', 'Cerliani|Leonardo|L|']
D000328:Adult D000368:Aged D001714:Bipolar Disorder D016022:Case-Control Studies D003430:Cross-Sectional Studies D003863:Depression D056324:Diffusion Tensor Imaging D005260:Female D006801:Humans D008279:Magnetic Resonance Imaging D008297:Male D008875:Middle Aged D066127:White Matter D055815:Young Adult
Diffusion tensor imaging Bipolar disorder Tbss Lithium Gsk-3