Structural and functional correlates of subsyndromes in chronic schizophrenia

Recent psychopathological studies consistently identified a delusional, a negative, and a disorganized subsyndrome in chronic schizophrenia. The aim of our studies was to investigate the subsyndromes with respect to their underlying cerebral changes using computed tomography (CT) and positron emission tomography (PET). In a CT study 50 DSM III schizophrenics were subgrouped according to four factors identified by a factor analysis of BPRS ratings. This procedure identified three chronic clusters (delusional ideation, negative symptoms, and disorganization) and one cluster with a remitting course of the disorder. Both the negative and the delusional subsyndrome were associated with a widening of the frontal interhemispheric fissure. Disorganization was associated with neurological soft signs, an increased ventricle brain ratio, and width of the 3rd ventricle. The same subgrouping was applied in a 18F-deoxyglucose PET study of 79 neuroleptic free DSM III schizophrenic patients and 47 healthy controls. The delusional subsyndrome was associated with a decreased hippocampal function, while the negative subsyndrome showed a prominent hypofrontality and left temporal cortex changes. Both the delusional and the negative subsyndrome were associated with a decreased activity in the medial frontal gyrus in comparison to the other schizophrenic patients and the healthy controls. The disorganized subsyndrome was characterized by an overactivity in the parietal cortex and motor strip and a decreased activity in the corpus callosum. These findings support the differentiation of three subsyndromes in chronic schizophrenia. The subsyndromes seem to be characterized by deviant patterns of cerebral alterations, rather than deficits in a single location.