While drinking coffee with caffeine each day does not appear to reduce sleepiness among people with Parkinson's disease, it may have a benefit in controlling movement, according to new research published in the August 1, 2012, online issue of Neurology®, the medical journal of the American Academy of Neurology. "Studies have shown that people who use caffeine are less likely to develop Parkinson's disease, but this is one of the first studies in humans to show that caffeine can help with movement symptoms for people who already have the disease," said study author Ronald Postuma, MD, MSc, with McGill University in Montreal and the Research Institute of the McGill University Health Center. Postuma is also a member of the American Academy of Neurology.

For the study, 61 people with Parkinson's disease who showed symptoms of daytime sleepiness and some motor symptoms were given either a placebo（对照剂） pill or a pill with 100 milligrams of caffeine two times a day for three weeks, then 200 milligrams twice a day for three weeks, which was the equivalent of between two and four cups of coffee per day.

After six weeks, the half that took the caffeine supplements averaged a five-point improvement in Parkinson's severity ratings compared to those who didn't consume caffeine. "This is a modest improvement, but may be enough to provide benefit to patients. On the other hand, it may not be sufficient to explain the relationship between caffeine non-use and Parkinson's, since studies of the progression of Parkinson's symptoms early in the disease suggest that a five-point reduction would delay diagnosis by only six months," said Postuma.

The caffeine group also averaged a three-point improvement in the speed of movement and amount of stiffness compared to the placebo group. Caffeine did not appear to help improve daytime sleepiness and there were no changes in quality of life, depression or sleep quality in study participants.

"The study is especially interesting since caffeine seems to block a malfunctioning brain signal in Parkinson's disease and is so safe and inexpensive," said Michael Schwarzschild, MD, PhD, of Massachusetts General Hospital in Boston, who wrote an accompanying editorial. "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 is also a member of the American Academy of Neurology.

The study authors noted that the length of the study was short and that the effects of caffeine may lessen over time.

The study was supported by the Canadian Institute of Health Research and the Webster Foundation.