There is a growing body of evidence which suggests that tobacco cigarette smoking (hereinafter, simply `smoking') is an independent predictor of suicide as well as suicidal behaviors such as suicidal ideation (thinking about committing suicide), suicidal planning, and suicide attempts. Such evidence is by no means overwhelming and the possibility of this being a causal association has yet to be determined. Still, many contributors in this area have proposed that cigarette smoking could affect suicide and suicide related outcomes through biological effects on serotonin metabolism. If nicotine and/or other chemicals found in tobacco are indeed an etiologic link between cigarette smoking and suicide, then one would expect other types of tobacco use to predict suicide and suicidal behaviors as well. Using US nationally representative cross-sectional data from the National Survey on Drug Use and Health (NSDUH) and longitudinal data from the National Epidemiological Study on Alcohol and Alcohol-Related Conditions (NESARC) I will test for the independent effects of cigarette smoking and smokeless tobacco use on subsequent suicide related outcomes with the hypothesis that cigarette smoking will predict suicidal behaviors while smokeless tobacco use will not. This is under the assumption that the possible causal effects of cigarette smoking on suicide risk have nothing to do with either the combustion of tobacco, the efficiency or speed with which nicotine or other agents would reach the brain, or other pharmacological differences between smoking tobacco and using smokeless tobacco. I will also challenge the smoking-suicide hypothesis by controlling for mental health co-morbidities using data from the Collaborative Psychiatric Epidemiology Surveys (CPES), in the US.Summary:A consistent finding within this dissertation is that smokeless tobacco use does not appear to alter the estimated risk of suicide related outcomes while cigarette smoking does. Also, while a considerable proportion of the relationship between cigarette smoking and suicide is explained by the presence of mental disorders, this work suggests smokers are still at increased odds of suicide regardless of their mental health. An important implication of these findings is that quitting cigarette smoking could potentially decrease one's risk of suicide. This dissertation found no evidence of those who recently quit smoking to be at a higher risk for suicide related outcomes, but future studies should build on this work by tracking changes in suicide risk in the proximal weeks and months following smoking cessation. Studies on non-United States or Western populations are also needed as the evidence in favor of a positive association between cigarette smoking and suicide is currently western-centric, and if a true biological association exists, one would expect to observe it in all countries where smokers are found.
Read
