People who smoked for 40 or more years were 46 percent less likely to develop Parkinson's disease than people who never smoked. Those who smoked for 30 to 39 years were 35 percent less likely to have the disease than nonsmokers. In contrast, those who smoked for one to nine years were only eight percent less likely to get the disease.

The risk of developing Parkinson's disease did not change based on how many cigarettes a person smoked per day.

Chen noted that studies have shown that smoking is not associated with a slower progression of the disease once Parkinson's develops or a reduced risk of death, so he said there is no evidence to support the use of nicotine or other smoking-related chemicals in treating the disease.

The study was supported by the National Institutes of Health, the National Institute of Environmental Health Sciences and the National Cancer Institute.

SOURCE American Academy of Neurology