Tobacco Smoking and Bipolar Disorder

Background: We sought to determine whethertobacco smoking is associated with bipolar
disorder.

Method: This case-control study carried out inAlava, in the north of Spain, included patients with a DSM-III-Rdiagnosis of bipolar disorder type I (N=51) and a representativesample of the normal population (N=517). Smoking history ofbipolar patients was assessed with the Fagerstrom Test forNicotine Dependence and was verified by family members of thepatients.

Results: The frequencies of ever smoking andcurrent daily smoking were, respectively, 63% (32/51) and 51%(26/51) for the bipolar patients and 45% (235/517) and 33%(169/517) for the control group (respective odds ratios [ORs] and95% confidence intervals [CIs] were OR=2.0, 95% CI=1.1 to 3.8 andOR=2.1, 95% CI=1.2 to 4.0). The differences were significant(p=.03 and p=.042, respectively) for bipolar versus controlmales. Bipolar disorder (in both genders) was also significantlyassociated (OR=4.4, 95% CI=1.7 to 11.9, p=.0015) with heavysmoking (more than 1 pack per day).

Conclusion: Despite its small sample size, thisstudy suggests that smoking may be more prevalent in bipolarpatients than in the normal population. Since most patientsstarted to smoke before the onset of illness, vulnerability tobipolar illness may make subjects vulnerable to become tobaccosmokers.