Demographics, clinical characteristics and cognitive symptoms of heavy smokers and non-heavy smokers in Chinese male patients with chronic schizophrenia

Many studies have shown a high smoking rate and cognitive impairment in patients with schizophrenia. The effects of smoking and nicotine intake on cognitive function in schizophrenia are still controversial. In this study, we divided patients into heavy smoking and non-heavy smoking groups and compared the clinical characteristics and cognitive symptoms between the two groups in Chinese male patients with schizophrenia. A total of 154 heavy smoking patients and 372 non-heavy smoking patients were recruited. They completed a detailed questionnaire including general and socio-demographic data. Positive and Negative Syndrome Scale (PANSS) was rated for psychopathology. The Fagerstrom Test for Nicotine Dependence (FTND) was used to assess the degree of nicotine dependence. Heavy smokers were younger, started smoking earlier and had a higher FTND total score than non-heavy smoking patients. Moreover, we found that heavy smokers had significantly lower negative symptom scores and cognitive factor scores than non-heavy smokers. Logistic regression analysis showed that cognitive factor score and age of initial smoking were significantly associated with heavy smoking. Linear regression analysis showed that cognitive factor score, age of initial smoking and dose of antipsychotics were significant predictors of the amount of smoking. Our findings suggest that there are significant differences in some demographic and clinical variables between heavy and non-heavy smokers in Chinese male patients with chronic schizophrenia. Moreover, heavy smokers have less cognitive symptoms, suggesting that heavy smoking may be beneficial for cognition of patients with schizophrenia.