Relationship of Obstetric Complications and Differences in Size of Brain Structures in Monozygotic Twin Pairs Discordant for Schizophrenia

OBJECTIVE: The aim of the study was to determine whether a history of obstetric complications and congenital minor physical anomalies are related to differences in the characteristics of brain structures observed within monozygotic twin pairs discordant for schizophrenia. METHOD: The size of the bilateral hippocampi and cerebral ventricles was studied by magnetic resonance imaging in 22 monozygotic twin pairs discordant for schizophrenia. Obstetric complications and minor physical anomalies were independently assessed through parental report and examination, respectively. RESULTS: Compared with the well co-twins, the ill twins consistently had smaller left and right hippocampi as well as larger left lateral ventricles and third ventricles. Relatively small left and right hippocampi were each significantly related to labor-delivery complications and to prolonged labor per se. Relatively large right lateral ventricle size and large total ventricle size were significantly related to labor-delivery complications, prolonged labor, neonatal complications, and total complications for the entire reproductive sequence. In contrast, these brain size differences were not significantly associated with pregnancy complications or minor physical anomalies. CONCLUSIONS: Trauma at the time of labor and delivery and especially prolonged labor appear to be of importance for brain structure anomalies associated with schizophrenia.