Structural brain alterations in bipolar disorder II: a combined voxel-based morphometry (VBM) and diffusion tensor...

Area of Science:

• Neuroimaging
• Psychiatry
• Brain Anatomy

Background:

• Bipolar disorder (BP) subtypes I and II often studied together, with focus on either grey matter (GM) or white matter (WM) integrity.
• Limited research specifically compares brain structural changes between BPII patients and healthy controls using combined imaging techniques.

Purpose of the Study:

• To investigate grey matter (GM) and white matter (WM) changes in BPII patients compared to healthy controls.
• To differentiate BPII-specific structural brain alterations from those observed in BPI type I.

Main Methods:

• Utilized voxel-based morphometry (VBM) for grey matter (GM) analysis.
• Employed diffusion tensor imaging (DTI) for white matter (WM) integrity assessment.
• Studied 20 euthymic BPII patients and 21 healthy controls matched for age and gender.

Main Results:

• VBM revealed diffuse decreases in GM in BPII patients, most notably in the right middle frontal and superior temporal gyri.
• DTI demonstrated widespread fractional anisotropy (FA) reduction across major WM tracts, including cortico-cortical association tracts, in BPII patients.
• Observed GM and WM changes in BPII were less prominent than previously reported for BPI type I.

Conclusions:

• BPII is associated with reduced GM volumes and altered WM integrity, primarily involving cortical structures and their associated tracts.
• These findings suggest distinct neurobiological underpinnings for BPII compared to BPI type I.
• The study's small sample size necessitates caution in generalizing the results.