Smoking habits in bipolar and schizophrenic outpatients in southern Israel

Background: Although rates of cigarette smoking have been found to be higher in schizophrenic and depressed patients than in the general population, data regarding rates in bipolar patients are limited. This study further examines the relationship between bipolar disorder and smoking and compares the rate of smoking in bipolar disorder patients with rates in schizophrenic patients and in the general population. Method: Seventy bipolar patients and 64 schizophrenic patients (diagnosed using DSM-IV criteria) treated at the largest specialized public bipolar and schizophrenia clinics in southern Israel were interviewed regarding their smoking habits. The interview included a questionnaire relating to personal information, past and present smoking, and drug abuse and the Fagerstrom scale for nicotine dependence. Data from these patients were also compared with data from the general Israeli population. Results: Data indicate that the rate of smoking does not appear to differ between bipolar (43.0%) and schizophrenic (45.0%) patients, whereas the rate for both patient groups is higher than that for the general Israeli population (27.5%). Smoking intensity was not found to be different between the 2 groups of patients. Conclusion: Smoking in patients with schizophrenia was suggested to be related to nicotine cholinergic dysfunction, but this suggestion cannot explain the equally high rates of smoking in bipolar patients. Schizophrenia, bipolar disorder, and smoking may all be related to dopamine transmission, and, therefore, dopaminergic interactions may provide a better explanation for the results.