Schizophrenia and smoking: impact on negative symptoms

Abstract

Introduction: it has been hypothesized that individuals with schizophrenia use nicotine to reduce negative symptoms and improve cognitive function. There is an inconsistency in the literature suggesting that nicotine could help decrease negative symptoms in schizophrenic patients. Objective: to investigate the effects of nicotine on the expression of the negative symptoms in smokers and non-smokers with schizophrenia. Methods: a cross sectional study, conducted between April and August 2016, 100 inpatients with schizophrenia (54 smokers and 46 non-smokers) diagnosed according to DSM-V, at Psychiatric Hospital of the Cross Lebanon, were compared to changes in clinical parameters using CDSS, PANSS, and nicotine dependence using FTND. The Student’s t-test was used to compare between 2 groups, while the ANOVA test was used to compare between 3 or more groups. For categorical variables, the chi-2 test was used. Results: the mean age was 47.16 years (SD = 7.14) for smokers compared to 47.02 years (SD = 7.92) for non-smokers. 64.8% of smokers were males versus 45.7% of non-smokers. Smoking (high nicotine dependence) significantly decreases the PANSS negative symptoms score between the 2 groups (p < .001), whereas it did not show a significant difference for the positive and the cognitive symptoms total score (p > .05 for both variables). Discussion and conclusion: this study is the first to investigate the relationship between the expression of negative symptoms in individuals with schizophrenia and smoking in Lebanon. Cigarette smoking rates remain remarkably high in patients with schizophrenia. Smoking is a complex process which involves psychopathological, biochemical and neuropharmacological aspects among schizophrenic patients. Further studies are needed to acknowledge these findings and the reasons behind it.