Anomalous asymmetry of fusiform and parahippocampal gyrus gray matter in schizophrenia: A postmortem study

Objective: Anomalies of structure and asymmetry of the parahippocampal gyru s (origin of the perforant path input to the hippocampal formation in the m edial temporal lobe) have been shown in some postmortem studies of schizoph renia, but previous studies have not included the fusiform gyrus (which may have a role in facial recognition and naming), adjacent to the parahippoca mpal gyrus on the ventral occipitotemporal surface. Method: The volumes of gray matter in the left and right parahippocampal and fusiform gyri were as sessed with a stereological point-counting technique in the temporal robes from formalin-fixed brains of 27 comparison subjects and 31 patients with s chizophrenia. Age was a covariate and gender was a factor in the analysis. Results: In relation to the comparison subjects, the schizophrenic patients (both sexes) had lower volumes of both the parahippocampal and fusiform gy ri on the left side. For both structures a left-greater-than-right volume a symmetry was present in the comparison subjects, but this asymmetry was rev ersed in the parahippocampal and fusiform gyri of the schizophrenic patient s. A sex difference was present with respect to age at onset-degree of anom aly of asymmetry for both gyri increased with age at onset in men but not i n women. Conclusions: The findings add substance to the view that the sex-r elated dimension of symmetry/asymmetry is integral to the disease process i n schizophrenia and draw attention to the fusiform gyrus as a structure of particular interest in relation to disturbances of identification and namin g in psychosis.