Smoking linked to suicide in bipolar disorder

Findings published in the Journal of Clinical Psychiatry suggest that smoking may be independently associated with suicidal behavior in subjects with bipolar disorder.

"The rate of smoking in people with bipolar disorder is much greater than in the general population, but the implications of smoking for the course of bipolar disorder have not been well studied," Dr. Michael J. Ostacher, of Massachusetts General Hospital, Boston, and colleagues write.

The researchers studied the medical records of 399 outpatients who were treated in a bipolar specialty clinic from December 1999 to October 2004. The team used the Affective Disorders Evaluation and the Mini-Interventional Neuropsychiatric Interview to assess diagnosis, mood state, course of illness, functioning, and the presence of other psychiatric disorders.

Overall, 155 (39 percent) of the subjects had a history of daily smoking.

An association was observed between having ever smoked and earlier age at onset of first depressive or manic episode, lower Global Assessment of Functioning scores, and higher Clinical Global Impressions-Bipolar Disorder scale scores.

Having ever smoked was also associated with a lifetime history of having made a suicide attempt (47 percent of smokers versus 25 percent of those who never smoked). Smokers were also more likely to have a history of comorbid disorders, including anxiety disorders, alcohol abuse and dependence, and substance abuse and dependence.

On further analysis, a previous suicide attempt or a history of substance abuse both remained significantly associated with smoking.

The fact that smoking remained associated with suicide attempts, even after consideration of the presence of other diseases and illness severity, "gives further evidence that there is a factor independent of mood, such as the impulsivity/aggression, associated with suicide, Ostacher and colleagues surmise.

"Whether this factor leads to the initiation of smoking in patients with bipolar disorder, or, instead, is a result of cigarette use itself cannot be answered by this study," they note.

SOURCE: Journal of Clinical Psychiatry, December 2006.