Smoking, nicotine dependence and psychiatric comorbidity--a population-based study including smoking cessation after three years

BACKGROUND: Evidence suggests that nicotine-dependent smokers are at increased risk for psychiatric comorbidity but general population data that included the number of nicotine dependence and withdrawal symptoms according to DSM-IV, the Fagerstrom Test for Nicotine Dependence (FTND), somatoform disorders and the number of psychiatric diagnoses are rare. The goal of the present study was to analyse relationships of smoking and nicotine dependence with psychiatric disease and whether psychiatric disease predicts the sustaining of smoking after three years. METHODS: Cohort study with a random adult population sample in a northern German region (N = 4075) including a baseline measurement of ever daily smokers aged 18-64 (n = 2458), a first follow-up of the current smokers at baseline (n = 1552) after 30 months and a second follow-up after 36 months. Measures included DSM-IV diagnoses by the Composite International Diagnostic Interview, FTND, smoking cessation by interview. RESULTS: Current daily smokers showed higher odds of a substance use disorder other than nicotine dependence compared with never smokers (odds ratio, OR, 4.6; confidence interval, CI, 2.9-7.2), affective (OR 1.8; CI 1.4-2.5), anxiety (OR 1.6; CI 1.2-2.0) or somatoform disorder (OR 1.4; CI 1.0-1.8). DSM-IV nicotine dependence and the FTND were positively related with the number of psychiatric diagnoses. Psychiatric comorbidity did not predict the maintenance of smoking or quitting. CONCLUSIONS: Findings of increased rates of mental disorders among smokers and nicotine-dependent smokers in the adult general population are supported by this study. The number of nicotine dependence and withdrawal symptoms are related to mental disorders. In addition, somatoform disorders show relationships with smoking similar to relationships with depressive or anxiety disorders. The intention to stop smoking should be proactively supported among these comorbid patients.