Limbic dysfunction in schizophrenia and mania - A study using F-18-labelled fluorodeoxyglucose and positron emission tomography

Background. Diagnostic classes (derived from CATEGO) can be correlated with regional brain metabolism in patients with major psychiatric disorders. Method. Seventeen patients with schizophrenia, 15 with mania, 10 with depression and 10 healthy volunteers were examined with positron emission tomography (PET) and F-18-labelled fluorodeoxyglucose, as a marker for glucose metabolism. The number of possible comparisons of regions of interest was reduced by principal-components analysis, and differences in factor scores were determined between diagnostic groups. Results. Four independent factors, representing distributed brain systems, emerged: an anterior-posterior (1), a left-right temporal (2), a temporofrontal (3), and a mediofrontal (4) system, of which (1), (2) and (3) were abnormal in schizophrenia, (1) and (2) in mania, and (1) in depression. Conclusions. Abnormal patterns of metabolism could be detected, in decreasing order, in schizophrenia, mania and depression. Some of these abnormalities are likely to be due to medication, but others will be associated with structural or functional abnormalities of the frontolimbic system in the diagnostic groups.