Possible Protection

That's the startling suggestion of a new U.S. study of families that also found NSAID use has no impact on the disease risk.

Previous studies have reported that consuming caffeine, smoking and taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen and naproxen may help prevent Parkinson's disease, according to background information in the study. But there's been little family-based research done to examine these links.

The new study, led by researcher Dana B. Hancock of Duke University Medical Center in Durham, N.C., included 356 Parkinson's patients (averaging about 66 years of age) and 317 of their family members (averaging almost 64 years of age).

The people with Parkinson's disease were 44 percent less likely to report ever smoking and 70 percent less likely to report current smoking compared with unaffected relatives, the study authors found.

"Increasing intensity of coffee drinking was inversely associated with Parkinson's disease," they added. "Increasing dosage and intensity of total caffeine consumption were also inversely associated, with high dosage presenting a significant inverse association with Parkinson's disease."

The study found no link between NSAID use and Parkinson's disease.

The findings are published in the April issue of the journal Archives of Neurology.

It's not known how smoking or caffeine consumption may help reduce the risk of developing Parkinson's disease.

"Given the complexity of Parkinson's disease, these environmental factors likely do not exert their effects in isolation, thus highlighting the importance of gene-environment interactions in determining Parkinson's disease susceptibility," the study authors wrote. "Smoking and caffeine possibly modify genetic effects in families with Parkinson's disease and should be considered as effect modifiers in candidate gene studies for Parkinson's disease."

The researchers doubt that smoking and caffeine protect from Parkinson's, but say the information offers clues about how environment works with genes to cause disease.

Dr. William Scott of the University of Miami school of medicine, who led the study, said the findings point clearly to dopamine -- a message-carrying chemical in the brain that falls to low levels in Parkinson's.

"Dopamine is important because both smoking and drinking caffeine affect dopamine in the brain," Scott said in a telephone interview.

Other researchers had noted that both smoking and drinking coffee seemed to reduce the risk of Parkinson's, but no one had tracked it in families prone to Parkinson's.

When a disease runs in families, it suggests that certain genes are causing it. "We need to consider these environmental associations while looking for genes that are involved in Parkinson's," Scott said.

Writing in the Archives of Neurology, Scott and colleagues said they studied 356 Parkinson's disease patients and 317 family members without the disease.

"Based on this paper we find that people who had Parkinson's disease were 40 percent less likely to say that they had ever smoked 100 cigarettes than their unaffected family members. A similar reduction was seen in the likelihood with coffee," Scott added.

"It seems that people with Parkinson's are less likely to have done these things over their lives -- to have smoked or to have consumed fairly large amounts of caffeine."

Mark Stacy of Duke University in North Carolina, who worked on the study, said it remains possible that coffee or cigarettes protect the brain.

But it is also likely, his colleagues said, that something else is going on. Perhaps people who later develop Parkinson's respond differently to the effects of caffeine and cigarettes.

"There is this notion, and it makes a lot of sense, that folks who are going to have have Parkinson's disease have lower levels of dopamine," said Duke neurologist Dr. Burton Scott, who also worked on the study.

"Those with higher levels of dopamine may be more likely to enjoy caffeine," he added.

The same team is now trying to pin down more of the genes associated with Parkinson's.

"I wouldn't make any lifestyle changes based on this, but I'd also think that with drinking my morning cup of coffee this morning that, hey there's at least one good thing that comes from this," William Scott said.

Parkinson's disease is caused when brain cells that produce dopamine die. The disease is progressive, affecting about 1 percent of people older than 65.

Symptoms start out with shaking and can progress to paralysis. There is no cure, although a number of drugs can make symptoms better for a time.

Exposure to pesticides is strongly linked with disease risk.

Source: Reuters