Orbitofrontal volume deficit in schizophrenia and thought disorder

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Orbitofrontal Cortex (OFC) structural abnormalities in schizophrenia are poorly understood due to anatomical variability.
• Previous research noted OFC sulcogyral pattern alterations but not volume associations with psychopathology or cognition.

Purpose of the Study:

• To investigate OFC subregion volume differences between schizophrenia patients and healthy controls (HC).
• To explore associations between OFC volumes, cognitive function (Iowa Gambling Task - IGT), and psychopathology in schizophrenia.

Main Methods:

• Used a novel, reliable parcellation method to manually delineate OFC subregions (Gyrus Rectus, Middle Orbital Gyrus, Lateral Orbital Gyrus) from MRI scans.
• Compared 24 schizophrenia patients with 25 HC subjects on cognitive tests (IGT, Wisconsin Card Sorting Test, Trail Making Test) and psychopathology assessments.
• Analyzed MiOG probability maps voxel-wise and classified OFC sulcogyral patterns.

Main Results:

• Schizophrenia patients exhibited an 11% smaller bilateral Middle Orbital Gyrus (MiOG) volume compared to HC.
• Smaller left MiOG volume correlated with worse positive formal thought disorder; smaller right MiOG correlated with longer illness duration.
• In HC, larger right MiOG volume was linked to better IGT performance, and larger left MiOG to faster Trail Making Test B performance.

Conclusions:

• Demonstrated a subregion-specific OFC gray matter deficit in schizophrenia, independent of sulcogyral pattern.
• OFC volume deficits are associated with specific psychopathological and illness duration factors in schizophrenia.
• Established a novel quantitative association between OFC volume and cognitive performance in healthy individuals.