Coffee and cigarette use: association with suicidal acts in 352 Sardinian bipolar disorder patients

Objective: Abuse of illicit drugs and alcohol is prevalent in bipolar disorder (BPD) patients, and is an adverse prognostic factor. Much less is known about correlates of nicotine and caffeine consumption, but tobacco smoking is tentatively associated with suicidal behavior. Methods: Retrospective analysis of demographic and clinical factors among 352 longitudinally assessed DSM-IV types I and II BPD patients contrasted patients with versus without consumption of nicotine or caffeine, based on univariate comparisons and multiple regression modeling. Results: Current smoking (46%) and coffee drinking (74% of cases) were common, and significantly and independently associated with suicidal acts [coffee: odds ratio (OR) = 2.42, 95% confidence interval (CI): 1.15-5.09; smoking: OR = 1.79, CI: 1.02-3.15; both p < 0.001]. Risk increased with more smoking (cigarettes/day; r(s) = 0.383; p < 0.0001) and greater coffee consumption (cups/day; r(s) = 0.312; p = 0.008). Neither intake was related to yearly rates of all episodes, depressions, or manias. Conclusions: This is the first report to associate suicidal acts with coffee consumption in BPD patients, and it confirmed an association with smoking. Pending further evidence, the findings underscore the importance of monitoring use of even legal and mildly psychotropic substances by BPD patients.