Season of birth and CT scan findings in schizophrenic patients

Abstract

Studies of season of birth in schizophrenic patients show a peak incidence during the winter and early spring months, with the lowest incidence during the late summer and early fall months. The majority of well-controlled studies have found an 8%-10% excess frequency of winter births relative to the general population. Many sources of error have been suggested (see Boyd et al. 1986 and Bradbury and Miller 1985 for reviews) to explain the phenomenon, but it remains one of the most consistently replicated findings in schizophrenia research. It has been suggested that winter-born schizophrenic patients contain an excess of those in whom “environmental” rather than genetic events play an etiological role (Boyd et al. 1986; Hare 1986). It has also been proposed that envitonrnental events influence ventricular size. In support of this view, Reveley et al. ( 1984) have reported that lateral ventricular enlargement is associated with a his-