A prospective study of coffee drinking and suicide in women
I. Kawachi, W. C. Willett, G. A. Colditz, M. J. Stampfer and F. E. Speizer
Channing Laboratory, Department of Medicine, Harvard Medical School, Boston, Mass., USA.
BACKGROUND: Among the many reported central nervous system effects of
long-term caffeine use is improvement in mood. OBJECTIVE: To examine
prospectively the relationship of coffee and caffeine intake to risk of
death from suicide. METHODS: We conducted a 10-year follow-up study (1980
to 1990) in an ongoing cohort of 86 626 US female registered nurses aged 34
to 59 years in 1980, who were free of diagnosed coronary heart disease,
stroke, or cancer. Information on coffee and caffeine intake was collected
by a semiquantitative food frequency questionnaire in 1980. Deaths from
suicide were determined by physician review of death certificates. RESULTS:
Fifty-six cases of suicide occurred during 832 704 person-years of
observation. Compared with non-drinkers of coffee, the age-adjusted
relative risk of suicide in women who consumed two to three cups per day
was 0.34 (95% confidence interval [CI, 0.17 to 0.68) and 0.42 (95% CI, 0.21
to 0.86) in women who consumed four or more cups per day (P for linear
trend=.002). These findings remained essentially unchanged after adjusting
for a broad range of potential confounding factors, including smoking
habit, alcohol intake, medication use (diazepam and phenothiazine), history
of comorbid disease (hypertension, hypercholesterolemia, or diabetes),
marital status, and self-reported stress. A strong inverse relationship was
similarly found for caffeine intake from all sources and risk of suicide.
CONCLUSIONS: The data suggest a strong inverse association between coffee
intake and risk of suicide. Whether regular intake of coffee or caffeine
has clinically significant effects on the maintenance of affect or the
prevention of depression merits further investigation in clinical trials
and population-based prospective studies.
