The Association of Cigarette Smoking With Depression and Anxiety: A Systematic Review

Abstract

Background:Many studies report a positive association between smoking and mental illness. However, the literature remains mixed regarding the direction of this association. We therefore conducted a systematic review evaluating the association of smoking and depression and/or anxiety in longitudinal studies.Methods:Studies were identified by searching PubMed, Scopus, and Web of Science and were included if they: (1) used human participants, (2) were longitudinal, (3) reported primary data, (4) had smoking as an exposure and depression and/or anxiety as an outcome, or (5) had depression and/or anxiety as the exposure and smoking as an outcome.Results:Outcomes from 148 studies were categorized into: smoking onset, smoking status, smoking heaviness, tobacco dependence, and smoking trajectory. The results for each category varied substantially, with evidence for positive associations in both directions (smoking to later mental health and mental health to later smoking) as well as null findings. Overall, nearly half the studies reported that baseline depression/anxiety was associated with some type of later smoking behavior, while over a third found evidence that a smoking exposure was associated with later depression/anxiety. However, there were few studies directly supporting a bidirectional model of smoking and anxiety, and very few studies reporting null results.Conclusions:The literature on the prospective association between smoking and depression and anxiety is inconsistent in terms of the direction of association most strongly supported. This suggests the need for future studies that employ different methodologies, such as Mendelian randomization (MR), which will allow us to draw stronger causal inferences.Implications:We systematically reviewed longitudinal studies on the association of different aspects of smoking behavior with depression and anxiety. The results varied considerably, with evidence for smoking both associated with subsequent depression and anxiety, and vice versa. Few studies supported a bidirectional relationship, or reported null results, and no clear patterns by gender, ethnicity, clinical status, length to follow-up, or diagnostic test. Suggesting that despite advantages of longitudinal studies, they cannot alone provide strong evidence of causality. Therefore, future studies investigating this association should employ different methods allowing for stronger causal inferences to be made, such as MR.

Prevalence of depression and anxiety among otolaryngology outpatients at Jordan University Hospital

“…This is consistent with the findings of a study done by El‐Mallakh et al, which showed a significant correlation between cigarette smoking and psychological disorders such as anxiety. On a systematic review of 148 studies regarding the association of cigarette smoking with depression and anxiety, the results varied considerably but few studies supported a bidirectional relationship with evidence for smoking to be both associated with subsequent depression and anxiety, and vice versa . The effect sizes and odds ratios of this finding suggest that it has a low to moderate clinical significance.…”

Depression among current, former, and never smokers from 2005 to 2013: The hidden role of disparities in depression in the ongoing tobacco epidemic

“…Although current data do not permit explication of a causal effect between smoking and depression, numerous studies suggest that smoking is associated with increased risk of the onset (Fergusson et al, 2003) and persistence (Bakhshaie et al, 2015) of depression, though the direction of effect cannot be examined here and while some data suggest depression is associated with smoking relapse (Zvolensky et al, 2015) other studies suggest no link between depression and relapse to smoking (Taylor et al, 2015). A nearly equal number of studies (Fluharty et al 2016) suggest the reverse pathway (Taylor et al, 2014); the relation appears to be bi-directional and possible mechanisms are not well understood (Goodwin (In Press). To ensure timely and effective prevention and treatment efforts, additional work should focus on elucidating targetable underlying factors associated with both forms of the smoking-depression relation.…”

Anxiety and Nicotine Dependence: Emerging Role of the Habenulo-Interpeduncular Axis

“…Nicotine, the major addictive component of tobacco, binds to and activates/desensitize nicotinic acetylcholine receptors (nAChRs) to elicit neural responses (see Box 2). Acutely, nicotine can induce a relief of anxiety and sustain tobacco use through positive emotional reinforcement (see also [8, 9]). The activation of circuits mediating the anxiolytic effects of nicotine may be considered an attempt at self-medication in people with ADs [10].…”