Prefrontal function and activation in bipolar disorder and schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• Bipolar disorder (BD) and schizophrenia (SCZ) exhibit unique speech and language deficits.
• Neural activation patterns underlying these deficits are not well understood and may not be diagnosis-specific.

Purpose of the Study:

• To investigate if language-associated prefrontal cortex activation patterns can differentiate between bipolar disorder and schizophrenia.
• To explore diagnostic specificity of neural activation in these disorders.

Main Methods:

• fMRI data from 42 BD patients, 27 SCZ patients, and 37 healthy controls (HC) using the Hayling Sentence Completion Test.
• Analysis using Statistical Parametric Mapping (SPM) 2, comparing sentence completion vs. rest and varying sentence constraint.
• Correlation of regional activations with clinical variables and set-shifting task performance.

Main Results:

• Patients with BD showed distinct insula and dorsal prefrontal cortex activation compared to SCZ patients.
• BD patients exhibited greater orbitofrontal cortex and ventral striatum recruitment than HC during increasing task difficulty.
• Ventral striatal and prefrontal activation gradients correlated with reversal errors in BD patients.

Conclusions:

• Brain activation during the Hayling task successfully differentiated BD patients from both SCZ patients and HC.
• Abnormalities in frontostriatal systems in BD are associated with set-shifting task performance.
• BD patients appear to engage emotional brain regions more than controls during this language task.