No association between breast-feeding and adult psychosis in two national birth cohorts

Background It has been proposed that breast-feeding might have a protective effect against the development of adult schizophrenia. Aims To-test this hypothesis. Method Using prospective data from two UK national birth cohorts, the feedi ng histories of those who later developed schizophrenia were compared with the remaining population at risk. Analyses in each cohort were considered t o be independent-tests of the hypothesis. Results There were no differences in feeding histories. In the 1946 birth c ohort (n=4447) 30 cases of DSM-III-R schizophrenia arose by age 43; 24.1% o f cases v. 23.6% of controls were entirely bottle-fed; 17.3% v. 12.3% were breast-fed for under I month; 58.6% v.64.1% were breast-fed beyond I month. In the 1958 cohort (n=18 856), 40 cases of CATEGO nuclear schizophrenia ar ose by age 28; 24.1% of cases v. 31.7% of controls were entirely bottle-fed ; 27.6% v. 24.9% were breast-fed for under I month; 48.3% v. 43.4% were bre ast-fed beyond I month. Conclusions These findings provide no evidence of any effect of breast-feed ing in protecting against the risk of later schizophrenia. Declaration of interest Funded by grants from the Stanley Foundation.