A study conducted by a team of scientists led by Lee Chun Hyuk from Ilji University included nearly 410,500 smokers (the average age of participants was 51.7 years, with 93.5% being men). All of them underwent three examinations as part of the Korean National Health Screening Program (NHSP) from 2009 to 2014. The median follow-up period after the last examination was 9.1 years, totaling about 3.59 million person-years.
The study participants were divided into several groups based on smoking dynamics: continuing to smoke (more than 267,000 people), resuming smoking (about 30,500 people), recently quit (more than 54,000 people), and long-term quitters (approximately 58,500 people). Information on new cases of Parkinson's disease and mortality was obtained from the relevant national registries. Competing risks regression models of Fine and Gray were used for data analysis, taking into account confounding factors.
During the follow-up, Parkinson's disease was diagnosed in 1,794 participants (0.44% of the total), while 31,203 people (7.6%) died. Statistical analysis showed that the risk of developing Parkinson's disease significantly increased for both recently and long-term quitters (sub-distribution hazard ratios were 1.60 and 1.61, respectively; p < 0.001). For those who resumed smoking, this figure did not differ significantly from continuing smokers (1.05; p = 0.603). At the same time, among long-term quitters, the risk of all-cause mortality significantly decreased (0.83; p < 0.001), while recently quitters showed a borderline decrease (0.97; p = 0.038), and for those who resumed smoking, the differences were not significant (0.97; p = 0.217).
The authors of the study concluded that the risk of Parkinson's disease is more dependent on current smoking status than on the cumulative exposure to tobacco smoke. The protective effect of smoking appears to persist even after a relatively short period of abstinence (about two years). Trends in mortality confirm the benefits of early smoking cessation, and data on the protective effect open up prospects for further research into its mechanisms and the development of safe cholinergic drugs for the prevention and treatment of Parkinson's disease.
Previously conducted studies have also shown that vaccination against tetanus may be associated with a reduced risk of Parkinson's disease, while the presence of ulcers and damage to the mucous membrane of the upper gastrointestinal tract is associated with an increased risk. Additionally, living in areas with abundant greenery in old age is associated with fewer first hospitalizations for Parkinson's and Alzheimer's diseases.
The post "Smoking cessation increased the risk of Parkinson's disease and reduced mortality" first appeared on K-News.
