Cortical thinning in bipolar disorder and schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Schizophrenia (SZ) and bipolar disorder (BD) exhibit overlapping clinical symptoms, including psychosis and cognitive impairments.
• The underlying pathophysiological similarities between SZ and BD remain largely unexplored.
• Investigating shared topographical abnormalities in cortical thickness can elucidate common disease mechanisms.

Purpose of the Study:

• To identify topographical overlap and segregation of cortical thickness abnormalities in patients with SZ and BD.
• To explore the association between cortical thinning and cognitive deficits in these patient groups.

Main Methods:

• Analysis of 3D-anatomical magnetic resonance imaging (MRI) datasets using FreeSurfer software.
• Comparison of cortical thickness and volume in 34 BD patients, 32 SZ patients, and 38 healthy controls.
• Correlation analysis between cortical thinning and neuropsychological assessments (psychomotor speed, executive functioning).

Main Results:

• Both SZ and BD patients displayed similar bilateral cortical thickness reductions in the inferior frontal gyrus (pars opercularis) and cingulate cortex.
• Disease-specific cortical thinning was observed: orbitofrontal cortex in BD, and dorsal frontal/temporal areas in SZ.
• Inferior frontal gyrus thinning correlated with cognitive deficits and age at onset in SZ, and with age at onset in BD.

Conclusions:

• Frontal cortex thinning may represent a shared biological feature in both schizophrenia and bipolar disorder.
• The association between cortical thinning and cognitive deficits highlights the functional relevance of these findings.
• Further research is needed to confirm a model of shared pathophysiological mechanisms across SZ and BD.