A prospective study of coffee drinking and suicide in women.
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.
Kawachi
I
I
Channing Laboratory, Department of Medicine, Harvard Medical School, Boston, Mass., USA.
Willett
W C
WC
Colditz
G A
GA
Stampfer
M J
MJ
Speizer
F E
FE
D000328:Adult; D000367:Age Factors; D000368:Aged; D000428:Alcohol Drinking; D000928:Antidepressive Agents / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D002423:Cause of Death; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D003069:Coffee; D015331:Cohort Studies; D015897:Comorbidity; D004327:Drinking Behavior; D005260:Female; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D013405:Suicide / Q000706:statistics & numerical data; D000092864:Suicide Prevention
D000928:Antidepressive Agents; D000697:Central Nervous System Stimulants; D003069:Coffee; D002110:Caffeine