Though an association between tobacco smoking and psychotic illness is well known, reasons for the association are more ambiguous. Recent research has associated smoking tobacco with an increased risk for developing psychosis (Gurillo, Jauhar, Murray, & MacCabe, 2015). The authors reviewed studies that reported rates of smoking in people with psychotic disorders compared with controls. They hypothesized that tobacco use is associated with increased risk of psychotic illness, that smoking is associated with an earlier age of onset of psychotic illness, and an earlier age of smoking is associated with increased risk of psychosis. Overall, though the association between tobacco use has been established, little attention has addressed if tobacco may actually increase the risk of psychosis.
Gurillo, Jauhar, Murray, and MacCabe’s (2015) analyzed 61 studies composed of 15,000 tobacco users and 273,000 controls. The results indicate that people who suffer from psychosis are three times more likely to smoke. Also, 57% of individuals with first episode psychosis were smokers. The risk of psychotic disorder increased modestly by daily smoking. In short, daily tobacco use was associated with increased risk of psychosis and with an earlier age of onset of psychosis.
Again, it is difficult to determine the direction of causality; rather an association between tobacco use and psychosis was supported. Also, the authors noted the possibility of publication bias might be present. Even still, the authors caution that smoking should be considered a possible risk factor for developing psychosis, and should not be construed as merely a consequence of the illness. Furthermore, consistent with the dopamine hypothesis, they suggest that nicotine exposure may increase the release of dopamine and cause psychosis to develop. Limitations include, a small number of longitudinal prospective studies and determining the exact consumption of other substances in some of the included studies. Of course the authors suggest more research is needed. Overall, they note that tobacco use may be a modifiable risk factor for psychosis, and every effort should be made to modify smoking habits in this population.
Gurillo, P., Jauhar, S., Murray, R. M., & MacCabe, J. H. (2015). Does tobacco cause psychosis? Systematic review and meta-analysis. Lancet Psychiatry, 2(8), 718-725.
Dannie S. Harris, M.A., M.A., M.A.Ed., Ed.S.
WKPIC Practicum Trainee