Moist smokeless tobacco (Snus) use and risk of Parkinson's disease

• Published in: International journal of epidemiology 2017-06, Vol.46 (3), p.872-880
• Main Authors: Yang, Fei, Pedersen, Nancy L, Ye, Weimin, Liu, Zhiwei, Norberg, Margareta, Forsgren, Lars, Trolle Lagerros, Ylva, Bellocco, Rino, Alfredsson, Lars, Knutsson, Anders, Jansson, Jan-Håkan, Wennberg, Patrik, Galanti, Maria Rosaria, Lager, Anton C J, Araghi, Marzieh, Lundberg, Michael, Magnusson, Cecilia, Wirdefeldt, Karin
• Format: Article
• Language: English
• Subjects: epidemiology; individual participant data; nicotine; Parkinson's disease; risk factors
• ISSN: 0300-5771; 1464-3685; 1464-3685
• DOI: 10.1093/ije/dyw294

Cigarette smoking is associated with a lower risk of Parkinson's disease. It is unclear what constituent of tobacco smoke may lower the risk. Use of Swedish moist smokeless tobacco (snus) can serve as a model to disentangle what constituent of tobacco smoke may lower the risk. The aim of this study was to determine whether snus use was associated with a lower risk of Parkinson's disease. Individual participant data were collected from seven prospective cohort studies, including 348 601 men. We used survival analysis with multivariable Cox regression to estimate study-specific relative risk of Parkinson's disease due to snus use, and random-effects models to pool estimates in a meta-analysis. The primary analyses were restricted to never-smokers to eliminate the potential confounding effect of tobacco smoking. During a mean follow-up time of 16.1 years, 1199 incident Parkinson's disease cases were identified. Among men who never smoked, ever-snus users had about 60% lower Parkinson's disease risk compared with never-snus users [pooled hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.28-0.61]. The inverse association between snus use and Parkinson's disease risk was more pronounced in current (pooled HR 0.38, 95% CI 0.23-0.63), moderate-heavy amount (pooled HR 0.41, 95% CI 0.19-0.90) and long-term snus users (pooled HR 0.44, 95% CI 0.24-0.83). Non-smoking men who used snus had a substantially lower risk of Parkinson's disease. Results also indicated an inverse dose-response relationship between snus use and Parkinson's disease risk. Our findings suggest that nicotine or other components of tobacco leaves may influence the development of Parkinson's disease.