Environmental tobacco smoke and Parkinson's disease

Background: Parkinson's disease is inversely associated with cigarette smoking, but its relation with passive smoking or environmental tobacco smoke exposure is rarely examined. Methods: Within a case–control study, we assessed the association between Parkinson's disease and living or working with active smokers. Cases were newly diagnosed with idiopathic Parkinson's disease (n = 154) from western Washington State in 2002–2008. Age‐ and sex‐matched controls (n = 173) were neurologically normal and unrelated to cases. Results: Compared with never active or passive tobacco smokers, we observed reduced Parkinson's disease risks for ever passive only smokers (OR, 0.34; 95% CI, 0.16–0.73), similar to those for ever active smokers (OR, 0.35; 95% CI, 0.17–0.73). Among persons whose only tobacco smoke exposure was passive smoking at home, risk was inversely associated with years exposed. Conclusions: These observations parallel those well established for active smoking. However, it remains unresolved whether a true protective effect of tobacco smoke, generally detrimental to health, underlies these associations. © 2011 Movement Disorder Society