Schizophrenia Res 2000 Nov 30

residence, and perinatal complications have each been identified as

environmental risk factors for the later development of schizophrenia,

schizoaffective disorder, and bipolar disorder.  A preliminary case-control

study also identified cat exposure in childhood as a possible risk factor. 

To assess selected environmental events, including childhood exposure to pets,

as possible risk factors for these diseases, 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 members of the National Alliance for the Mentally Ill,

and whose children had been diagnosed with schizophrenia, schizoaffective

disorder, or bipolar disorder.  The controls were mothers randomly selected

from the same telephone exchanges. For five of the 19 major variables, there

were statistically significant differences between case and controls: fever

during pregnancy, complications during delivery, city or suburban residence at

birth, cat ownership 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 residence 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.  Additional research is needed to ascertain how such environmental

risk factors interact with genetic risk factors.  Understanding these could