Effects of Smoking on Patients with Parkinson's Disease

ABSTRACT

BACKGROUND: The cause of idiopathic Parkinson's disease (IPD) is unknown. Recent studies suggest that IPD occurs less frequently in smokers than in non-smokers, but remains a controversial topic. We performed a case-control study to investigate the relationship between IPD and smoking in Korea. METHODS:The smoking histories of 624 IPD patients were compared with 622 age- and sex-matched control subjects at the Asan Medical Center. Detailed informa-tion on smoking behavior was identified from a questionnaire and self report. A conditional logistic regression was used to calculate the odds ratio (OR) and control for potential confounds. RESULTS: With "never-smokers" as the refer-ence category, there was an inverse association between past-smokers and IPD (OR 0.617, p=0.029), and a stronger inverse association of IPD with current-smokers (OR 0.389, p<0.001). When smokers were stratified by the interval "since quitting", there was an inverse association between those who stopped smoking more than 10 years ago and IPD (OR 0.753, p=0.31), and a greater inverse relationship with those who stopped smoking 1 to 10 years (OR 0.489, p=0.017). A significant trend of decreased risk of IPD with pack-years of smoking was detected. CONCLUSIONS: This study suggests that IPD occurs less often in smokers than in non-smokers. The inverse dose-response relationship between smoking and IPD provides indirect evidence that smoking is biologically protective.