Seasonal variation of suicide in South Africa

Seasonal trends in South African suicide incidence were investigated with a view to ascertaining whether they are consistent with those in the northern hemisphere regarding: (1) the existence of the expected pattern; (2) this pattern being more pronounced for less urbanized groups; and (3) the presence of a secondary fall peak for youth and females. Log-linear modelling was performed to investigate the effect of month and relevant demographic variables on the suicide counts. The 16,389 nationally registered suicide deaths during 1980-1989 were analysed. The expected pattern, with a peak in the spring (that is, in September/October) or summer and a trough in winter, was present. This pattern was more pronounced for a sub-group that is less urbanized and for another sub-group with a relatively low standard of living. The secondary peak in autumn was not present for youth or females. In the northern hemisphere, this secondary peak has been ascribed to sociodemographic factors associated with the commencement of the academic year and (for females) bioclimatic factors associated with gender-specific biological circannual rhythms. The fact that the academic year commences in summer in South Africa indicates that the present findings are consistent with the former explanation.