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Abstract
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BACKGROUND: The influence of seasons on mood disorders is controversial.
OBJECTIVE: To examine monthly variations in admissions for mania and depressions including variations with sex and age and correlations with frequencies of suicides.
METHODS: All admissions for mania or depression (N=4341) in a population of 1,800,000 with 35,285 admissions in the years 1992-1996 were analysed. All 14,503 suicides in Norway the years 1969-1996 were also analysed.
RESULTS: Admissions for depression had a significant monthly variation for women (chi(2)=29.78, df=11, P<0.005) with the highest peak in November and for men (chi(2)=19.69, df=11, P<0.05) with the highest peak in April. Among women increasing age correlated negatively with the range of monthly observed/expected ratios (r(s)=-0.943, N=6, P<0.01) and with a of maximal monthly observed/expected ratio (r(s)=-0.943, N=6, P<0.01). Among men suicides correlated with admissions for depression (r=0.647, N=12, P<0.05) and mania (r=0.678, N=12, P<0.05).
LIMITATIONS: The time of admission to hospital are not identical to onset of affective episode. The study was done retrospectively. No sociocultural or physical environmental data were investigated.
CONCLUSION: A hypothesis of an influence of seasons on mood disorders is supported. Younger women seem to be especially vulnerable.
Language: en |