Diffusion tensor imaging in euthymic bipolar disorder - A tract-based spatial statistics study.
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.



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.



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.



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.



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.
University of Groningen, University Medical Center Groningen, Department of Psychiatry, Groningen, The Netherlands; Radiology Morphological Solutions, Berkel en Rodenrijs, The Netherlands. Electronic address: b.c.m.haarman@rug.nl.
Bartholomeus C M 'Benno'
BCM'
Haarman
University of Groningen, University Medical Center Groningen, Department of Psychiatry, Groningen, The Netherlands.
Rixt F
RF
Riemersma-Van der Lek
University of Groningen, University Medical Center Groningen, Department of Psychiatry, Groningen, The Netherlands; University of Groningen, University Medical Center Groningen, Department of General Practice, Groningen, The Netherlands.
Huibert
H
Burger
University of Groningen, University Medical Center Groningen, Department of Radiology, Groningen, The Netherlands.
Jan Cees
JC
de Groot
Erasmus MC, Department of Immunology, Rotterdam, The Netherlands.
Hemmo A
HA
Drexhage
University of Groningen, University Medical Center Groningen, Department of Psychiatry, Groningen, The Netherlands.
Willem A
WA
Nolen
University of Groningen, Neuroimaging Center, Groningen, The Netherlands; Institute du Cerveau et de la Moelle épinière, Paris, France.
Leonardo
L
Cerliani
D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003863:Depression; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D066127:White Matter / Q000000981:diagnostic imaging*; D055815:Young Adult
Bipolar disorder; Diffusion tensor imaging; Gsk-3; Lithium; Tbss