A B S T R A C TObjectives. This study examined the relation between smoking and suicide, controlling for various confounders.Methods. More than 50 000 predominantly White, middle-aged and elderly male health professionals were followed up prospectively with biennial questionnaires from 1986 through 1994. The primary end point was suicide. Characteristics controlled for included age, marital status, body mass index, physical activity, alcohol intake, coffee consumption, and history of cancer.Results. Eighty-two members of the cohort committed suicide during the 8-year follow-up period. In age-adjusted analyses with never smokers as the comparison group, the relative risk of suicide was 1.4 (95% confidence interval [CI] = 0.8, 2.3) among former smokers, 2.6 (95% CI = 0.9, 7.5) for light smokers (<15 cigarettes/day), and 4.5 (95% CI = 2.3, 8.8) among heavier smokers. After adjustment for potential confounders, the relative risks were 1.4 (95% CI = 0.9, 2.4), 2.5 (95% CI = 0.9, 7.3), and 4.3 (95% CI = 2.2, 8.5), respectively.Conclusion. We found a positive, dose-related association between smoking and suicide among White men. Although inference about causality is not justified, our findings indicate that the smoking-suicide connection is not entirely due to the greater tendency among smokers to be unmarried, to be seden- 1 Although the nature of the relation between cigarette smoking and disease has been most convincingly demonstrated for physical illness, several researchers have linked smoking to mental illness, especially depression.
2-14Almost a dozen studies have shown a significant association between smoking and suicide. However, many of these studies were small and did not control for characteristics common to both smokers and persons who commit suicide.13,15-25 For example, only 2 prospective studies with more than 20 suicides controlled for alcohol intake-and these yielded conflicting results. 18,22 In this article, we present data on more than 50 000 men followed up prospectively for 8 years. Our analysis controlled for several potentially important behavioral, situational, and demographic factors that have been identified in the suicide, smoking, and depression literature. In addition, the investigation evaluated the relation between suicide and smoking, while taking into account changes in smoking status during follow-up. The study also examined prospectively the contribution of developing cancer to the association between smoking and suicide.