Moist smokeless tobacco (Snus) use and risk of Parkinson's disease.
Level 3 - non-randomized controlled study
Pooled individual participant analysis of prospective cohort studies
PubMed 27940486 · doi:10.1093/ije/dyw294
What was done
Individual participant data were collected from seven prospective cohort studies including 348,601 men followed for a mean of 16.1 years. Investigators used multivariable Cox regression and random-effects meta-analysis models to estimate hazard ratios for incident Parkinson's disease in relation to Swedish snus use. The primary analyses were restricted to never-smokers to eliminate potential confounding from tobacco smoking.
What was found
During follow-up, 1,199 incident Parkinson's disease cases were identified. Among non-smoking men, ever-use of snus was associated with about a 60% lower Parkinson's disease risk compared with never-use (pooled HR 0.41, 95% CI 0.28-0.61). The inverse association was more pronounced in current users (pooled HR 0.38, 95% CI 0.23-0.63), moderate-to-heavy amount users (pooled HR 0.41, 95% CI 0.19-0.90), and long-term users (pooled HR 0.44, 95% CI 0.24-0.83).
Why it matters
Because snus delivers tobacco constituents without combustion, these findings suggest that nicotine or other components of tobacco leaves, rather than combustion products, may explain the inverse association between tobacco use and Parkinson's disease.
Limits
The study included only men, so findings may not generalize to women. As an observational study, it cannot establish causality, and specific active chemical constituents were not directly isolated.
Cited by
- supports Scientific data shows that nicotine reduces the risk of Parkinson's disease.