Longtime smoking cuts Parkinson's risk in half.

It makes you look cool, too! From CNN:

It's a catchy headline – smoking cuts Parkinson's risk dramatically – and it appears to be true, but researchers at the National Institute of Environmental Health Science don't want you to start smoking.

"Nobody should advocate smoking to prevent Parkinson's disease," said Dr. Honglei Chen, a tenure-track investigator at the Institute. "It’s important to make that very, very clear."

The study, released today in the journal Neurology looked at the lifetime smoking history of more than 300,000 people, and confirmed the inverse relationship between smoking and Parkinson's disease, established in earlier scientific studies. But, researchers say they've found a critical new piece to the puzzle: It appears to be the length of time one has been a smoker – not the number of cigarettes smoked – that has the most effect on disease risk reduction.

"People who smoked more than 40 years had a 46 percent decrease in Parkinson's disease risk," said Chen. "Whereas people who smoked between one and nine years had only an 8 percent decrease in risk."

Chen, the lead study author, and his colleagues cannot yet identify the reasons behind this staggering link, but say when they are able to determine which chemicals in the cigarettes seem to be have a protective effect, they hope to be able to develop a drug that can mimic the effects of smoking, without the harmful risks.