Kraepelinian and non-Kraepelinian schizophrenia subgroup differences in cerebral metabolic rate

Abstract

We studied two subtypes of schizophrenia, the Kraepelinian subtype ( n=10) characterized by an unremitting and severe course and the non-Kraepelinian subtype ( n=17) characterized by a remitting course and some periods of self-care. Patients were assessed with positron emission tomography (PET) with 18F-deoxyglucose (FDG) and high-resolution magnetic resonance imaging (MRI). A group of 32 age- and sex-matched normal volunteers served as comparison subjects. During the FDG tracer uptake period, patients performed a serial verbal learning task. MR images were segmented into gray, white and cerebrospinal fluid regions, and warped to average normal coordinates. PET images were coregistered to the MR images and similarly warped for analysis. Kraepelinian subtype patients were characterized by lower metabolic rates in the temporal lobe and cingulate gyrus, and lower fronto/occipital ratios than non-Kraepelinian subtype patients. Exploratory statistical probability mapping also revealed lower metabolic rates in the right striatum in Kraepelinian versus non-Kraepelinian patients. These differences could not be attributed to differences in age, symptom severity, task performance during FDG uptake, or severity of involuntary movements. Factor analysis of the cortical surface identified significantly lower temporal lobe metabolic rates in Kraepelinian patients than non-Kraepelinian patients. A combined frontal/temporal deficit or greater cortical change may be associated with poorer longitudinal course.