Cigarette Smoking, Stages of Change, and Major Depression in the Canadian Population

Objective: To describe the 12-month prevalence of major depression in relation to smoking status, nicotine dependence levels, commitment to quit, attempts to quit, and maintenance of smoking cessation in the Canadian general population. Method: Data from Public Use Microdata File of the Canadian Community Health Survey: Health and Well-Being were used. The Composite International Diagnostic Interview-Short Form (CIDI-SF) for major depression was used to assess depressive disorder status. The survey also included a smoking module. There were 49 249 respondents assessed by the CIDI-SF, of whom 10 236 were administered the smoking module. Analyses used appropriate measures to deal with survey design effects. Result: The prevalence of major depression was highest in current smokers, followed by ever smokers, former smokers, and was lowest in the never smokers. This pattern persisted after stratification for age and sex. For quitting, the prevalence of major depression was highest among people who tried to quit, followed by those who considered quitting, those who quit in the past year, and lowest among those who maintained their smoking cessation status for longer than I year. The prevalence of depression among those with a high nicotine dependence level, as assessed by the Fagerstrom Tolerance Questionnaire, was about twice that of people with a low nicotine dependence level. Conclusion: The strikingly high prevalence of major depression among current smokers who are young, trying to quit, and with high nicotine dependence levels in the general population indicates that further longitudinal exploration of this topic is urgently needed.