Hippocampal Deformities in Schizophrenia Characterized by High Dimensional Brain Mapping

OBJECTIVE: Abnormalities of hippocampal structure have been reported in schizophrenia subjects. However, such abnormalities have been difficult to discriminate from normal neuroanatomical variation. High dimensional brain mapping, which utilizes probabilistic deformations of a neuroanatomical template, was used to characterize disease-related patterns of changes in hippocampal volume, shape, and asymmetry. METHOD: T₁-weighted magnetic resonance scans were collected in 52 schizophrenia and 65 comparison subjects who were similar in age, gender, and parental socioeconomic status. The schizophrenia subjects were clinically stable at the time of assessment. RESULTS: Significant abnormalities of hippocampal shape and asymmetry (but not volume after total cerebral volume was included as a covariate) were found in the schizophrenia subjects. The pattern of shape abnormality suggested a neuroanatomical deformity of the head of the hippocampus, which contains neurons that project to the frontal cortex. The pattern of hippocampal asymmetry observed in the schizophrenia subjects suggested an exaggeration of the asymmetry pattern observed in the comparison subjects. No correlations were found between the magnitude of hippocampal shape and asymmetry abnormality and the severity of residual symptoms or duration of illness. CONCLUSIONS: Schizophrenia is associated with structural deformities of the hippocampus, which suggest a disturbance of the connections between the hippocampus and the frontal cortex. However, the magnitude of these deformities are not related to severity or duration of illness.