Can a Cup a Day Keep Parkinson's Away?
July 19, 2001 -- Evidence continues to mount that daily coffee drinking may protect against Parkinson's disease, a nervous system disorder characterized by tremors and rigidity that affects as many as one million Americans.
So far, several studies have shown an association between high caffeine consumption by men and a lower risk of developing Parkinson's disease. Now a new study adds to that data by showing that both men and women who drink coffee daily appear to be less likely to be diagnosed with Parkinson's. The more men drink, the lower their risk of Parkinson's; women, however, only see their risk lowered when they drink in moderation -- 1-3 cups per day.
"There is some biological experimental evidence that caffeine does protect against [brain cell death]," says Alberto Ascherio, MD, lead author of the new report in the July issue of Annals of Neurology.
Ascherio and colleagues studied the diet and lifestyles of more than 47,000 women and about 88,500 men who were free of Parkinson's disease. They then followed both groups for 10-16 years to see how many developed the disease.
A common thread among the 288 people eventually diagnosed with Parkinson's was a low level of caffeine use, says Ascherio, associate professor of nutrition and epidemiology at Harvard School of Public Health.
But the findings are not proof that drinking plenty of caffeine actually does anything to prevent Parkinson's from developing. In fact, one theory for why people who have Parkinson's are not big coffee drinkers is that they lack a brain chemical called dopamine that stimulates pleasure centers in the brain. People who lack this chemical may be less likely to drink coffee simply because they get little pleasure from it.
Similarly, Ascherio also found that people with Parkinson's consumed less alcohol in the years before their diagnosis and were less likely to smoke cigarettes.
But it's unlikely that dopamine is the whole explanation. One large study that found an association between low intake of caffeine and higher rates of Parkinson's had tracked people for as long as 30 years before they developed the disease. Scientist think dopamine levels don't start dropping until 5-7 years before Parkinson's symptoms start, so Ascherio says it's doubtful that those people had lost their sense of pleasure 30 years before the onset of the disease.
He believes researchers should not dismiss the possibility that long-term caffeine consumption may be doing something that keeps the brain and its cells from falling victim to Parkinson's. "Unfortunately, this is a very difficult hypothesis to prove or disprove," he tells WebMD.
Neurologist Paul Greene, MD, cautions people to be careful not to read too much into the study's conclusions.
The fact that the association between caffeine and Parkinson's is not as strong for women makes it seem highly unlikely that caffeine is an effective form of protection against the disease, says Greene, associate professor of neurology at Columbia-Presbyterian Hospital, in New York.