Fetal brain development and later schizophrenia.

Computed tomography and magnetic resonance imaging studies have shown cerebral ventricular enlargement and a decreased volume of temporal lobe structures in a proportion of schizophrenic patients. Neuropathological investigations confirm these findings and also show diminished volume of the hippocampus and abnormal pre-alpha cell clusters in the parahippocampal gyrus. Compared with controls, schizophrenic patients are more likely to have minor physical anomalies, to have a history of obstetric complications, and to have been born in the late winter. Together the evidence regarding structural brain abnormalities and epidemiology suggests that a significant proportion of cases of schizophrenia have their origins in fetal or neonatal life. The mechanisms involved in the aberrant neurodevelopment remain obscure but some impairment of neuronal migration is an appealing hypothesis.