Parental Age and Schizophrenia

Reports that schizophrenics have older parents than non-schizophrenics (Barry, 1945; Goodman, 1957; Johanson, 1958; Gregory, 1959) are of considerable importance. If valid, they provide evidence for environmental causes of schizophrenia, and by analogy with other conditions where parental age effects have been noted may give some indication of the nature of these causes. There are, however, inconsistencies in these studies: thus Johanson and Gregory found a significant association between advanced paternal age and schizophrenia, but failed to confirm the maternal age effect noted by Barry and Goodman. These differences indicate the need for further investigation and this paper describes such a study.