Brain gray matter phenotypes across the psychosis dimension

Area of Science:

• Neuroimaging
• Psychiatry
• Brain Anatomy

Background:

• Schizophrenia (SZ), schizoaffective disorder (SAD), and psychotic bipolar I disorder (BD-P) are distinct psychotic disorders.
• Understanding their neurobiological underpinnings, specifically gray matter (GM) differences, is crucial for diagnosis and treatment.
• Previous research indicates structural brain abnormalities in these conditions, but direct comparisons across a psychosis dimension are limited.

Purpose of the Study:

• To investigate whole brain and regional gray matter (GM) phenotypes across the schizophrenia-bipolar disorder psychosis dimension.
• To compare GM volumes in individuals with SZ, SAD, and BD-P against healthy controls (HC).
• To examine volumetric differences within the psychosis spectrum using advanced neuroimaging techniques.

Main Methods:

• Voxel-based morphometry (VBM) and FreeSurfer (FS) were used to analyze 3T T1 MPRAGE MRI scans.
• Participants included 19 SZ, 16 SAD, 17 BD-P, and 10 HC.
• Statistical comparisons were made to identify significant GM differences between groups.

Main Results:

• Schizophrenia (SZ) exhibited extensive cortical GM reductions, especially in fronto-temporal regions, compared to HC.
• Schizoaffective disorder (SAD) showed overlapping but less extensive GM reductions than SZ.
• Psychotic bipolar I disorder (BD-P) did not differ from HC in GM volumes; BD-P had larger fronto-temporal volumes than SZ.

Conclusions:

• Gray matter deficits, particularly in fronto-temporal regions, characterize SZ but not BD-P.
• SAD displays intermediate GM deficits, overlapping with SZ.
• VBM and FS methods yielded largely consistent results for cortical GM but showed some divergence for subcortical regions.