Major depression and secondhand smoke exposure

J Affect Disord. 2018 Jan 1;225:260-264. doi: 10.1016/j.jad.2017.08.006. Epub 2017 Aug 12.


Background: Epidemiological studies have consistently linked smoking to poor mental health. Among non-smokers, some studies have also reported associations between secondhand smoke exposure and psychological symptoms. However, an association between secondhand smoke exposure and depressive disorders has not been well established.

Methods: This analysis used cross-sectional data from a series of 10 population surveys conducted in Canada between 2003 and 2013. The surveys targeted the Canadian household population, included a brief structured interview for past year major depressive episode (MDE) and included items assessing secondhand smoke exposure. We used two-stage individual-level random-effects meta-regression to synthesize results from these surveys.

Results: Over the study interval, about 20% of non-smokers reported substantial exposure to secondhand smoke. In this group, the pooled annual prevalence of MDE was 6.1% (95% CI 5.3-6.9) compared to 4.0% (95% CI 3.7-4.3) in non-smokers without secondhand smoke exposure. The crude odds ratio was 1.5 (95% CI 1.4-1.7). With adjustment for a set of potential confounding variables the odds ratio was unchanged, 1.4 (95% CI 1.2 - 1.6).

Conclusions: These results provide additional support for public health measures aimed at reducing secondhand smoke exposure. A causal connection between secondhand smoke exposure and MDEs cannot be confirmed due to the cross-sectional nature of the data. Longitudinal studies are needed to establish temporal sequencing.

MeSH terms

  • Adult
  • Canada
  • Comorbidity
  • Cross-Sectional Studies
  • Depressive Disorder, Major / epidemiology*
  • Depressive Disorder, Major / etiology
  • Female
  • Humans
  • Male
  • Mental Health / statistics & numerical data
  • Middle Aged
  • Odds Ratio
  • Public Health
  • Risk Factors
  • Smoking / adverse effects
  • Smoking / epidemiology*
  • Tobacco Smoke Pollution / adverse effects
  • Tobacco Smoke Pollution / statistics & numerical data*


  • Tobacco Smoke Pollution