Major Depression and Stages of Smoking

Abstract

RECENT epidemiologic studies have reported an association between smoking and major depression,^1-3 replicating earlier observations from clinical samples^4,5 and studies linking smoking to depressive symptoms.^6-8 Several alternative explanations for the association have been proposed. It has been suggested that major depression plays a causal role in smoking—increasing the risk for smoking initiation and the progression to regular and heavy smoking and decreasing the potential for smoking cessation.^3,9-11 At the core of this causal explanation is the notion of self-medication, ie, that smokers use nicotine to medicate their depressed mood and that the reinforcing effects of nicotine's mood-altering characteristic are especially powerful in depressed smokers. Contending explanations include (1) a causal influence of smoking on major depression, based on the possible effects of long-term nicotine exposure on neurobiologic systems that are implicated in the etiology of depression³; and (2) the effects of shared environmental or genetic factors that predispose to both smoking and major depression.^3,9