PATTERNS OF CORTICAL ACTIVITY IN SCHIZOPHRENIA

Eighty-three patients with schizophrenia and 47 healthy controls recei ved positron emission tomography (PET) with 18F-2-deoxyglucose uptake while they were executing the Continuous Performance Test (CPT). The e ntire cortex was divided into 16 regions of interest in each hemispher e, four in each lobe of the brain, and data from corresponding right a nd left hemispheric regions were averaged. Data from the schizophrenic patients were subjected to a factor analysis, which revealed five fac tors that explained 80% of the common variance. According to their con tent, the factors were identified and labelled 'parietal cortex and mo tor strip', 'associative areas', 'temporal cortex', 'hypofrontality' ( which included midfrontal and occipital areas) and 'frontal cortex'. H emispheric asymmetry was only confirmed for the temporal cortex. Facto r weights obtained in, the schizophrenic group were applied to the met abolic data of the healthy controls and factor scales computed. Schizo phrenics were significantly more hypofrontal than the controls, with h igher values on the 'parietal cortex and motor strip' factor and a tre nd towards higher values in the temporal cortex. A canonical discrimin ant analysis confirmed that the 'hypofrontality' and 'parietal cortex and motor strip' factors accurately separated the schizophrenic group from the healthy controls. Hemispheric asymmetry was only confirmed fo r the temporal lobe. Significantly higher factor scores for the left t emporal lobe in schizophrenics than in normals were obtained when calc ulated for the right and left hemisphere separately. Taken together, o ur results confirm the importance of hypofrontality as a pattern of co rtical metabolic rate and point to the potential importance of parieta l and motor strip function in schizophrenia.