OBJECTIVE: The authors hypothesized that cortical gray matter volume
reduction in schizophrenia is greatest in the heteromodal association
cortex. This area comprises a highly integrated, reciprocally
interconnected system that coordinates higher order cortical functions.
METHOD: Total brain and regional gray matter volumes were calculated in 46
schizophrenic patients and 60 age and sex-matched comparison subjects by
using magnetic resonance images. Disease specificity was examined by
assessing 27 patients with bipolar disorder. Approximations to the
dorsolateral prefrontal cortex, inferior parietal lobule, and superior
temporal gyrus were selected as regions of interest for the heteromodal
association cortex. Occipital and sensorimotor areas were used as
comparison regions to test the hypothesis for regional specificity.
RESULTS: Gray matter volume was reduced in schizophrenic patients in index
regions even after covariance for overall brain volume, sex, and age.
Bipolar disorder patients did not exhibit heteromodal gray matter
reduction. Comparison regions did not differ among the three groups. Global
gray matter volume was not different among groups after covariance for
global brain volume. Comprehensive individual region post hoc analysis
found no additional gray matter differences. CONCLUSIONS: These findings
support the theory of disproportionate reduction of gray matter volume in
the heteromodal association cortex specific to schizophrenia.