The Association Between Season of Birth and the Risk for Schizophrenia

Abstract

Many epidemiologic studies have been conducted to discover factors that might bear on the origins of schizophrenia. In general, the results of these studies have been contradictory. One consistent finding, however, is an association between season of birth and the risk for schizophrenia. This paper reports a test of the hypothesis that season of birth is associated with the risk for subgroups of the schizophrenic population. The results of regression analyses of data from Monroe County, New York, are reported. All white residents who were reported to have been diagnosed schizophrenic for the first time during the period January 1, 1969, to December 31, 1971, and who were hospitalized at least one day in the five-year period following the first schizophrenic diagnosis formed the group of schizophrenic patients. The population data used for the denominators of the incidence rates consisted of all white residents living in Monroe County, New York, as of April 1, 1970. An effect of month of birth on the risk for schizophrenia was related to the sex and the age of subsets of the whole population.

Seasonality of births in schizophrenia and bipolar disorder: a review of the literature

“…Kim et al (1994) (n=1606) and d 'Amato et al (1996) (n= and Roche, 1975) and 2256 (Parker and Neilson, 1976), but the other two had small sample sizes 668) both reported that family history had no effect on the seasonality of births. Ten of the of 918 (Pulver et al, 1981) and 350 (García Hildebrandt, 1992). Interestingly, three of these remaining studies, including those with the largest samples Beckmann, 1993, n=1229; four studies were carried out in Southern Hemisphere countries.…”

“…At least 8.3. Procreational habits 13 studies of birth seasonality in schizophrenia or manic-depressive psychosis have corrected for the Huntington (1938) appears to have been the first to explain the seasonal birth pattern in individage incidence or age prevalence effects, but the winter-spring birth excess was still statistically uals with schizophrenia by postulating that their parents have an idiosyncratic seasonal conception significant (Hare, 1975b(Hare, , 1978Pulver et al, 1981Pulver et al, , 1983Watson et al, 1982Watson et al, , 1984aShur and Hare, pattern. As described by James (1978), ''in the summer, people wear fewer clothes in bed, and... 1983;O'Callaghan et al, 1991;Rodrigo et al, 1992;Aschauer et al, 1994;Kim et al, 1994; a schizoid spouse is more likely then to notice his (or her) co-spouse there and accordingly to initiate Pallast et al, 1994;Tam and Sewell, 1995).…”

“…Hare and Price (1968) proposed that ''an Several researchers have postulated that the winter-spring birth excess observed in schizoincreased robustness associated with the schizophrenic genotype may lead to an increased survival phrenia and bipolar disorder might be caused by variations in internal chemistry or neural developof winter-born babies prone to schizophrenia''. Conversely, Pulver et al (1981), noting that ment brought about by seasonal variations in light. For example, Turnquist (1993) proposed that ''seainsufficient attention has been directed to the months of deficit births rather than excess births, sonal changes in maternal hormonal levels'' could affect neuronal pruning or other developmental proposed that in the summer and fall there might be ''a seasonally varying factor that increases the events and thereby ''provide an explanation for the greater winter birthrate among schizophrenic risk to fetal loss of individuals with genes predisposing to schizophrenia''.…”

Cytokine and growth factor involvement in schizophrenia—support for the developmental model

“…7 Moreover, some neuropathological findings have suggested that this disease arises from defective embryological development in selective brain areas. 8,9 Relatively subtle changes in migration and/or differentiation of neural progenitor cells may produce brain atrophy, reduction of interneurons, and brain malformation.…”

Season of Birth in Psychiatry

“…There is a correlation therefore between low genetic risk, perinatal infections, ventricular enlargement and the likelihood of winter birth. The winter-birth patients, moreover, appear to have a prevalence of negative symptoms [36] and an early onset of the disease [37].…”