Tobacco dependence is the most common substance use disorder in people with mental illness. Smoking and depression are firmly associated and both represent major health problems.

The aim of the study was to assess association between smoking status and 12-months depression in representative sample of the general Latvian population.

The study was a part of health monitoring survey, a collaborative project between Baltic States and Finland, which monitors health related behaviours; the questionnaire included structured interview and depressive module of the Mini International Neuropsychiatric Interview. Descriptive statistics and binary regression model were applied.

A total of 3003 15-64 years old persons were interviewed by using face-to-face data collection tool. The 12-month prevalence of depression in the general population of Latvia was 7.3% (95% CI 6.4–8.3). Of those who were current smokers the 12-months prevalence of depression comprised 9.8% (95% CI 8.0–11.8), in occasional smokers 12.7% (95% CI 8.1–19.5), in quitters and non-smokers population – 6.6% (95% CI 4.6–9.4) and 6.4% (95% CI 5.3–7.8), accordingly. Current smokers had 2.0 times (95% CI 1.4-2.8; p<0.00) and occasional smokers had 2.6 times (95% CI1.5-4.6; p=0.001) higher risk of having depression in the past 12 months. The odds of having depression were 1.8 times (95% CI 1.4–2.5; p<0.00) higher in women who smoke compare to men.

Clinical evaluationson presence of depression for all patients who smoke are needed. Further population-based studies are necessary to determine the causal effects between smoking and depression.