The antecedents of psychoses: a case-control study of selected risk factors

Winter birth, urban birth and/or childhood residence, and perinatal complic ations have each been identified as environmental risk factors for the late r development of schizophrenia, schizoaffective disorder, and bipolar disor der. A preliminary case-control study also identified cat exposure in child hood as a possible risk factor. To assess selected environmental events, in cluding childhood exposure to pets, as possible risk factors for these dise ases, a case-control telephone survey was carried out by the University of Maryland Survey Research Center for 264 mothers of cases and 528 mothers of matched controls. The cases were randomly selected mothers who were member s of the National Alliance for the Mentally ill, and whose children had bee n diagnosed with schizophrenia, schizoaffective disorder, or bipolar disord er. The controls were mothers randomly selected from the same telephone exc hanges. For five of the 19 major variables, there were statistically signif icant differences between cases and controls: fever during pregnancy, compl ications during delivery, city or suburban residence at birth, cat ownershi p between birth and age 13, and breast-feeding. In a multivariate logistic regression including these five variables, each variable made a significant contribution. The finding of perinatal complications, urban/suburban resid ence at birth, and cat ownership in childhood as risk factors for the later development of psychoses confirmed previous studies. Previous research on breast-feeding as a risk factor has yielded contradictory results. Addition al research is needed to ascertain how such environmental risk factors inte ract with genetic risk factors. Understanding these could lead to better tr eatments and possible prevention strategies. (C) 2000 Elsevier Science B.V. All rights reserved.