Suicidal behavior, smoking, and familial vulnerability.

INTRODUCTION

Smoking is a well-established correlate of suicidal behavior. It is not known if familial risk factors contribute to this association.

METHODS

Data were obtained via semistructured interviews with 1,107 twin fathers, 1,919 offspring between ages 12-32 years, and 1,023 mothers. Familial vulnerability to nicotine dependence and suicidal behavior was modeled via father and maternal self-report of these behaviors. Multinomial logistic regression models were computed with and without familial risk factors to estimate the association between offspring ever smoking, regular smoking, nicotine dependence, and a 4-level offspring suicide variable: (a) none, (b) ideation, (c) ideation + plan, and (d) ideation + plan + attempt or ideation + attempt. All models were stratified by gender and adjusted for sociodemographics, familial risk factors including parental suicidal behavior, nicotine dependence, and conduct disorder, and offspring conduct disorder, depression, alcohol abuse/dependence, and illicit drug abuse/dependence.

RESULTS

After adjusting for covariates and familial risk factors, ever smoking was not significantly associated with suicidal behavior in males and females. In males, regular smoking was associated with ideation + plan (odds ratio [OR] = 5.47; 95% CI: 1.05-28.60), and in females, regular smoking was associated with ideation + plan + attempt or ideation + attempt. In both genders, nicotine-dependent smoking was associated with ideation + plan + attempt or ideation + attempt (males: OR = 6.59; 95% CI: 1.91-22.70, females: OR = 3.37; 95% CI: 1.25-9.04). Comparison of models with and without familial risk factors indicated that there is no mediation of smoking status and suicidal behavior by familial risk.

CONCLUSIONS

Smoking and nicotine dependence are correlated with suicidal behaviour. Contributions from familial risk factors did not significantly alter this association.