Scientific studies have confirmed that tobacco addiction, like other addictive substances, is a chronic brain disease with a complex pathogenesis, currently believed to be a combination of genetic and environmental factors. Epidemiological studies have shown that the prevalence of smoking in the Chinese adult population is about 30-40%, with men significantly higher than women at 50%. One particular group of people is of concern: the prevalence of smoking in the psychiatric population is significantly higher than in the general population, being 1-2 times higher. The exact cause is still unclear, and there are several hypotheses: 1. Genetic factors hypothesis. Some studies suggest that schizophrenia and smoking addiction share genes, and that patients suffering from schizophrenia have more factors causing tobacco addiction than the general population. 2. Environmental factors cause high smoking rates, such as patients being hospitalized for long periods of time, having little interaction with people, and relieving anxiety by smoking. 3, psychological factors, such as being discriminated against, unfair treatment, etc. make patients come to smoke increased. 4, self-medication. Some studies have shown that in smoking and non-smoking psychiatric patients, the severity of clinical symptoms and cognitive deficits are not the same, patients smoke to relieve symptoms and achieve therapeutic purposes. The main harmful substance in tobacco is not nicotine but other chemicals that are burned, and it is believed that hundreds of harmful substances are produced when tobacco is burned. Smoking does not only damage peripheral organs, but also the central nervous system, and cognitive function is significantly impaired in schizophrenic patients who smoke compared to non-smokers. Focus on your health and stay away from tobacco.