Bipolar disorder and tobacco smoking: Categorical and dimensional clinical correlates in subjects from the Brazilian bipolar research network

BACKGROUND: People with bipolar disorder (BD) have high rates of smoking. However, the scientific literature examining the association between clinical outcomes in BD and tobacco smoking is still limited and there are conflicting results. The objective of the current study was to comprehensively investigate associations between BD and tobacco smoking in a large Brazilian sample. METHODS: This study evaluated 336 outpatients from the Brazilian Bipolar Research Network, which is a collaboration between three large academic centers in Brazil. MAIN FINDINGS: Regarding the categorical analysis (i.e. current smokers versus non-smokers), tobacco smokers showed: 1) a higher percentage of individuals identifying as Non-Caucasians; 2) a longer duration of illness; 3) a longer duration of untreated illness; 4) more severe manic symptoms; 4) a stronger family history of mood disorder; and 6) a higher current prevalence of alcohol/substance use disorder. The dimensional analysis in smokers (i.e. number of cigarettes per day versus clinical variables) found a positive correlation between number of cigarettes per day and a) age, b) age at onset of BD, c) duration of illness, and d) current diagnosis of panic disorder. CONCLUSION: This study found important clinical correlates of tobacco smoking in BD subjects. We observed that the variables associated with current smoker status (categorical approach) are not necessarily correlated with number of cigarettes per day (dimensional approach). Duration of illness appears to be a particularly relevant clinical variable in the association between BD and tobacco smoking.