Season of birth and Schneider-oriented diagnosis of affective disorder.

Most earlier studies and all recent studies on national samples have shown that compared with live births in the control population, schizophrenic patients have a significant excess of birth rates in the winter or early months of the year. In contrast, only some of the early research efforts and only some of the national studies (in England and Wales as well as for certain decades in Sweden) have demonstrated that the same holds true for patients with affective psychosis. The present German study, carried out on affective disorder diagnosed in a strongly Kurt Schneider-oriented clinic, found (as did most Scandinavian research on national samples) that there was no significant overrepresentation of births in the winter or early months of the year for all types of affective disorder, neurotic as well as psychotic. Thus, the findings on Schneider-diagnosed affective disturbances were similar to those on Schneider-diagnosed schizophrenia reported elsewhere.