In the Canadian-led study, researchers set out to see if caffeine could help overcome what's called daytime somnolence, a symptom that affects some patients with the progressive neurological disease.
While they didn't find an appreciable wake-up effect among subjects taking caffeine, the researchers were surprised to find that java's main ingredient appeared to enhance patients' mobility.
"What was significant was the movement improvement," said principal investigator Dr. Ronald Postuma, a neurologist at McGill University Health Centre's research institute. "And this was present both on motor symptoms, but also on the objective scoring in the motor exam."
To conduct the study, 61 people with Parkinson's disease who showed symptoms of daytime sleepiness and some motor impairment were randomly assigned to receive either a placebo pill or a caffeine tablet. Participants chosen for the study were not big coffee drinkers — on average, they drank only about one cup of joe per day.
Those in the treatment group took a pill containing 100 milligrams of caffeine twice daily for three weeks, then 200 milligrams twice daily for three weeks — the equivalent of between two and four cups of coffee per day.
After six weeks, those getting caffeine supplements averaged a five-point improvement in Parkinson's severity ratings compared to those getting placebo, the researchers report in Wednesday's online issue of the journal Neurology.
"The biggest problem with Parkinson's disease that affects people's lives is the slowing of movements," Postuma said from Montreal. "You move less, you have smaller movements and you do them more slowly. And then you also have some stiffness and rigidity.
"And those were the things that improved," he said. "So patients would move faster, their movements were more fluid, they can get dressed quicker, they can walk quicker. Their muscles are less stiff because their underlying disease is essentially improved."
The caffeine group averaged a three-point improvement in the speed of movement and amount of stiffness compared to the placebo group. However, there were no changes in reported quality of life, depression or sleep quality in participants.
Still, Postuma said what's exciting about the findings is that the motor-related benefits from caffeine are similar to those seen with medications used to treat Parkinson's, a disease caused by the loss of dopamine-producing cells in the brain.
"But in this case, we got it with a natural product," he said, noting that caffeine in coffee, tea, colas and other products has long been ingested by humans without any major adverse health effects.
"And then its cost is minimal. You can buy it in Canada, in a tablet over the counter at the pharmacy, for 10 cents a pill. (That's) a lot cheaper than a cup of coffee, in fact — and a huge cost advantage compared to other pharmaceutical products."
Research has shown that people who regularly use caffeine have a lower risk of developing Parkinson's, although the reasons for that aren't fully understood. And while there are several theories, it also isn't clear why caffeine would help improve a patient's movements.
Postuma said a much longer study with a larger pool of patients is needed to determine the extent of caffeine's benefits and whether they can be sustained over time.
Dr. Quincy Almeida, director of the movement disorders research and rehabilitation centre at Wilfrid Laurier University, called the work "exciting, innovative research," but agreed a longer-term study is needed.
Almeida pointed out that the study focused on patients who were not big coffee drinkers. "So if they're not used to more than a single cup, it begs the question of whether we should expect the same results in people already drinking two to three to four cups of coffee a day."
And because the initial buzz provided by caffeine tends to wear off over time, even in healthy people, that might mean the need for ever-increasing doses, he said from Waterloo, Ont.
"There could be some pretty serious side-effects," including even more pronounced exhaustion after a person's caffeine high crashes and jitteriness that could adversely affect already-impaired movement.
Another key question, he said, is whether all people with Parkinson's would react in the same way to caffeine as those with daytime sleepiness, who make up only a proportion of patients with the disease.
"Should we really extrapolate and assume that caffeine should be generalized as a useful thing for all Parkinson's patients? Or maybe it's just this unique group because they only tested people that specifically had the symptom."
In an accompanying editorial in Neurology, Dr. Michael Schwarzschild of Massachusetts General Hospital noted that caffeine appears to block a malfunctioning brain signal in Parkinson's disease and is safe and inexpensive.
"Although the results do not suggest that caffeine should be used as a treatment in Parkinson's disease, they can be taken into consideration when people with Parkinson's are discussing their caffeine use with their neurologist," Schwarzschild writes.
Postuma agreed, saying the findings should not spur Parkinson's patients to start drinking lots of coffee, even though the results look promising.
"If caffeine helps Parkinson's disease, it could potentially reduce the dose of other medications and all kinds of other benefits that we could only see over the long term," he said, referring to the extended study he hopes his team can get funding to conduct.
"It's crazy, we've actually found something — caffeine — which is widely available as a treatment. So we really have to follow it up."
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