Daily cigarette smokers are 1.82 times more likely to have suicidal thoughts or to attempt suicide, compared with those who had smoked in the past, results from a large prospective study have demonstrated.
Previous studies have suggested that there is a link between cigarette smoking and suicidal behavior, but this study controlled for major depression and alcohol or drug use disorders, reported the researchers, who were led by Naomi Breslau, Ph.D., of the department of epidemiology at Michigan State University in East Lansing.
“Limitations of the study are that we have no data on completed suicide and that the number of suicide attempts was small and therefore was combined with suicidal thoughts,” the researchers said (Arch. Gen. Psychiatry 2005;62:328-34).
“To analyze these rare outcomes, a much larger sample and longer follow-up period are needed. Whether the results can be extrapolated to attempted or completed suicide is uncertain. However, suicidal behaviors are established predictors of completed suicide. These antecedents and their potential etiologies are therefore of scientific and public health interest,” they said.
Dr. Breslau and her associates prospectively studied 990 men and women aged 21-30 who were randomly selected from a Michigan HMO.
The researchers asked study participants about lifetime history of psychiatric disorders and daily smoking and administered the National Institute of Mental Health Diagnostic Interview Schedule for DSM-III-R at their baseline interview in 1989 and in follow-up interviews in 1992, 1994, and 1999-2001.
Current smokers were defined as those who reported smoking within the preceding 12 months of an assessment; past smokers were defined as those who had smoked previously but not in the preceding 12 months.
Of the 990 men and women, 63% were female, 80% were white, 29% completed college, and 46% were married.
The researchers found that current daily smokers were significantly more likely to have suicidal thoughts or to attempt suicide, compared with past smokers (odds ratio of 1.82 vs. odds ratio of 1.09, respectively).
After adjusting for suicidal predisposition indicated by prior suicidality and controlling for prior psychiatric disorders, current daily smokers were significantly more likely to have suicidal thoughts or to attempt suicide, compared with past smokers (odds ratio of 1.74 vs. odds ratio of 1.14, respectively), the investigators said.
The National Institute of Mental Health provided funding for the study.