People who smoke tobacco are less likely to be diagnosed with Parkinson’s disease before the age of 75 than nonsmokers, scientists said.
The report, pooling data from 11 studies, found that U.S. smokers of cigarettes, as well as individuals who had quit as much as 25 years before, had at least a 13 percent to 32 percent decrease in risk, compared with people who never smoked. The reason wasn’t clear, the researchers said.
About 50,000 Americans a year are diagnosed with Parkinson’s, according to the National Institute of Neurological Disorders and Stroke. In the disease, cells in the part of the brain that controls movement die or malfunction. The new report, which confirms a previously suggested tie between smoking and reduced Parkinson’s risk, may help scientists learn the causes of the disorder.
“It’s clearly a bad idea for patients as well as the general public to consider smoking helpful for Parkinson’s, but it can help us understand the disease further,” said Michael Schwarzschild, an associate professor at Harvard Medical School in Boston, who wasn’t affiliated with the study.
It may be that nicotine protects neurons, said the lead author, Beate Ritz, or it may be that people who are prone to Parkinson’s disease are less likely to take risks, such as by smoking. The study didn’t look at whether those who were already diagnosed with the disease were helped by nicotine.
The link also could be that something environmental or genetic is determining both the personality and the smoking, Schwarzschild said.
The brain regions affected by Parkinson’s are those that process dopamine, one of the brain’s reward chemicals, which is involved in addictive behavior.
