Initiation of daily smoking and nicotine dependence in schizophrenia and mood disorders

This study replicates, using more refined methodology, the indications of prior studies that patients with schizophrenia show a greater frequency of tobacco smoking than patients with mood disorders. The sample included 66 patients with schizophrenia and 51 patients with a mood disorder who were admitted at a state hospital in Kentucky. The control group included 404 community subjects. Ever daily smoking was studied using logistic regression. Survival analyses of age of onset of daily smoking (AODS) were performed controlling for several variables including education level. Nicotine dependence was measured with a scale. The prevalence of ever and current daily smoking was respectively 92 and 83% for patients with schizophrenia, 78 and 65% for patients with mood disorders, and 47 and 26% for controls. Before the age of 20, the three populations appear to have a similar risk of smoking initiation. However, after the age of 20, the initiation rate of daily smoking for patients with schizophrenia was higher than in patients with a mood disorder, or controls. Among daily smokers, there were no differences in nicotine dependence between patients with schizophrenia and those with a mood disorder. Schizophrenia was associated with a greater probability of ever daily smoking than mood disorders and with higher rates of initiation of daily smoking after 20 years old.