Seasonal and Weather Factors in Parasuicide

BACKGROUND: Seasonal variation in suicide and parasuicide has previously been reported. Few investigations have examined whether meteorological factors could influence suicidal behaviour, and the inconclusive results produced may be due to a variety of methodological problems. The present study overcomes some previous difficulties and tested whether parasuicide admission rate is related to weather variables. METHOD: Over 12,000 admissions for parasuicide were analysed by month, season, and in relation to meteorological data, which were measured close to the admitting hospital. RESULTS: Marked seasonal (P < 0.001) and monthly (P < 0.001) variations in mean daily parasuicide numbers were seen in women but not men. Small but highly significant correlations were demonstrated between parasuicide rate and weather parameters (P < 0.01), which were more marked in women (P < 0.01). These effects were additional to the monthly variation (P < 0.05). CONCLUSIONS: Weather has a small influence on parasuicide. Gender differences in body temperature regulation might account for the sex difference seen.