Distinguished Frontal White Matter Abnormalities Between Psychotic and Nonpsychotic Bipolar Disorders in a Pilot...

Area of Science:

• Neuroimaging
• Psychiatry
• White Matter Microstructure

Background:

• Shared white matter (WM) abnormalities exist between bipolar disorder (BD) and schizophrenia (SZ).
• WM heterogeneity in BD, particularly concerning psychosis, is crucial for understanding BD-SZ boundaries.
• Previous studies on WM microstructure in psychotic (PBD) and non-psychotic BD (NPBD) yielded limited results.

Purpose of the Study:

• To investigate white matter (WM) microstructural differences between psychotic bipolar disorder (PBD) and non-psychotic bipolar disorder (NPBD).
• To explore the potential role of WM abnormalities in differentiating PBD from schizophrenia (SZ).
• To identify specific WM tracts affected in PBD.

Main Methods:

• Diffusion tensor imaging (DTI) was used to assess WM microstructure.
• Participants included 8 individuals with PBD, 8 with NPBD, and 22 healthy controls (HC).
• Tract-based spatial statistics (TBSS) and region of interest (ROI) analyses were performed.

Main Results:

• Increased radial diffusivity (RD) was observed in PBD compared to NPBD within specific WM tracts (corpus callosum, corona radiata).
• NPBD showed significant age-associated increases in RD.
• The increased RD in PBD compared to NPBD was consistent across middle age.

Conclusions:

• Preliminary findings suggest severe frontal WM disconnection in PBD, impacting interhemispheric and cortico-limbic circuits.
• These microstructural differences may offer insights into the pathophysiology of PBD at the BD-SZ diagnostic boundary.
• Replication in larger samples is needed to validate these findings.