Objectives: Cigarette smoking in individuals with bipolar disorder has been associated with suicidal behavior, although the precise relationship between the two remains unclear.
Methods: In this prospective observational study of 116 individuals with bipolar disorder, we examined the association between smoking and suicidality as measured by Linehan's Suicide Behaviors Questionnaire (SBQ) and prospective suicide attempts over a nine-month period. Impulsivity was measured by the Barratt Impulsiveness Scale.
Results: Smoking was associated with higher baseline SBQ scores in univariate and adjusted analyses, but was not significant after statistical adjustment for impulsivity in a regression model. A higher proportion of smokers at baseline made a suicide attempt during the follow-up period (5/31, 16.1%) compared to nonsmokers (3/85, 3.5%); p = 0.031, odds ratio = 5.25 (95% confidence interval: 1.2-23.5). Smoking at baseline also significantly predicted higher SBQ score at nine months.
Conclusions: In this study, current cigarette smoking was a predictor of current and nine-month suicidal ideation and behavior in bipolar disorder, and it is likely that impulsivity accounts for some of this relationship.