Mental Disorder and Season of Birth: Comparison of Psychoses with Neurosis

Abstract

Barry and Barry (1961, 1964) have reviewed the evidence for an association between season of birth and the major psychoses. Their figures show that, with a single exception, every study has found an excess (though not always a significant excess) of schizophrenic and manic-depressive patients born between January and April, and a deficit born between May and August, compared with the control populations. The single exception was their own study (1964) on schizophrenic patients in private mental hospitals, a finding which led them to conclude either that the private class of patient is protected from some adverse seasonal influence or that schizophrenic patients come chiefly from a subgroup of the population which has a comparatively high birth rate during the first four months of the year. Norris and Chowning (1962) drew attention to the fact that the seasonal distribution of births in a general population may vary appreciably from year to year in a particular country and from place to place within that country in any one year, and suggested that such variations make difficult any comparison between births of patients and of a large general population taken over a number of years, the procedure which had hitherto been adopted.