SYMPTOM DIMENSIONS AND BRAIN MORPHOLOGY IN SCHIZOPHRENIA AND RELATED PSYCHOTIC DISORDERS

The heterogeneity of symptoms in schizophrenia may reflect heterogenei ty of underlying pathophysiological mechanisms. Factor analytic studie s have consistently identified three symptom factors, psychotic, negat ive and disorganized, as independent dimensions of schizophrenic psych opathology. This study examined the relationship of these symptom dime nsions with volumes of specific brain regions. One-hundred and sixty-s ix schizophrenia spectrum patients were clinically evaluated with the Comprehensive Assessment of Symptoms and History (CASH) and scanned wi th a 1.5 Tesla magnetic resonance imaging scanner. Regions of interest (ROIs) were manually traced on 5 mm and 3 mm coronal slices by a sing le technician, blind to all aspects of subject identity. Correlations between ROI volumes and indices of symptom severity were determined. A nalyses of covariance were then used to test for specific relationship s between each of the three symptom dimensions and ROI volumes. Tests were made of each dimension, controlling for all others. Overall sympt om severity was significantly correlated with larger ventricle volumes (lateral, third and temporal horns) and smaller temporal lobe, hippoc ampal and superior temporal gyral volumes, Both psychotic and negative symptom severity predicted increased third ventricular volume. Psycho tic symptom severity uniquely predicted decreased superior temporal gy ral volume as well as increased temporal horn volume. Within the psych otic symptom dimension, hallucinations alone predicted left superior t emporal gyral volume. No significant associations between disorganized symptoms and any ROIs were demonstrated. These results provide clues to the localization of specific brain regions underlying symptom clust ers in schizophrenia, and provide further validating evidence for the construct of independent dimensions of psychopathology within schizoph renia and related psychotic disorders.