For Information Contact:
Dr. G. Webster Ross
(808) 524-3595
Ronald Yonemoto
(808) 433-0100
Embargoed by the Journal of the American Medical Association
For Release on Tuesday, May 23, 2000 at 4:00 P.M., EST
STUDY LINKS COFFEE INTAKE AND PARKINSON'S PREVENTION
HONOLULU -- Reporting in the May 24/31 issue of the Journal of the American Medical Association, U.S. Department of Veterans Affairs (VA) researchers and colleagues have discovered a possible link between increased coffee intake and a lower risk of Parkinson's disease (PD).
"The exciting thing about this study is that we now have even more evidence that environmental factors alter the risk of developing Parkinson's disease," said lead author G. Webster Ross, M.D., staff neurologist at the VA Medical Center in Honolulu.
"We have medications that treat the symptoms of PD, what we really need is a way to prevent it or slow it down. Our results support the idea that this is possible." The study did not determine the exact cause of coffee's apparent beneficial effect. It may, however, help other scientists to develop new a understanding of the mechanisms of PD, Ross said.
Ross and his colleagues from the VA and Kuakini Medical Center used data from the participants in the Honolulu Heart Program, an ongoing study started in 1965 to examine heart disease and stroke. More than 8,000 Japanese-American men (with an average age of 53) joined the study in 1965 and have received regular follow-up examinations since then. As part of the initial examination, a dietician collected nutritional data, including levels of coffee consumption. This information was updated in 1971 to assess any changes. Ross' team compared this data to diagnosis rates of PD among the men, evaluated from 1991 to 1996.
Using the initial dietary examination, the researchers found an annual incidence rate of 10.5 cases of PD per 10,000 person-years (one year of life for one person) among non-coffee drinkers. The incidence rate dropped to 5.5 for those drinking 4 to 8 ounces per day, 4.7 for those drinking 12 to 16 ounces, 3.6 for those drinking 20 to 24 ounces, and 1.7 for those drinking more than 28 ounces. Results from the 1971 examination showed a similar drop in incidence.
Adjusting for other factors, the researchers estimated that non-coffee drinkers were two to three times as likely to develop PD as coffee drinkers consuming 4 to 24 ounces per day. When compared to men who drank the highest amount of coffee (28 oz. or more per day), nondrinkers were five times as likely to develop PD. These rates include an adjustment by the researchers to account for cigarette smoking, a previously identified protective agent for PD.
In order to assess the cause of coffee's seemingly protective nature, researchers analyzed total caffeine intake including caffeine from sources other than coffee. Findings were similar for other sources of caffeine, but the results were not statistically significant because of a small sample size, Ross said.
Researchers found no association between other key nutrients in coffee, such as niacin, and risk of PD. There was also no correlation between milk and sugar, common coffee additives, and PD. Adjustment for alcohol consumption, hypertension, cholesterol level, calorie intake, and saturated fat level had no effect on the results.
Ross suggested several hypotheses that might explain the findings. Previous studies have identified a personality type that tends to have lower PD rates. People in this category tend to be "thrill-seeking" and are more closely associated with destructive behaviors such as smoking and heavy alcohol consumption.
Ross said high coffee intake may be another characteristic of the personality and the chemical systems in the brain that contribute to this personality type also impart a resistance to developing PD.
He also suggested that caffeine may have a pharmacological effect that counters some of the earliest symptoms of PD. Finally, it is possible that caffeine may actually have a protective effect against the nerve cell destruction that causes PD. "Hopefully this will lead to more basic research on caffeine and its effect on areas of the brain affected by Parkinson's disease," he said.
Although the study found a beneficial effect to coffee, Ross warned "it is too early to recommend coffee drinking to prevent PD.
"While our study found a strong correlation between coffee drinkers and low rates of Parkinson's disease, we have not identified the exact cause of this effect. I'd like to see these findings used as a basis to help other scientists unravel the mechanisms that underlie Parkinson's onset."
Parkinson's disease is a chronic neurological condition that afflicts more than half a million Americans, with 50,000 new diagnoses each year. The average age of onset is 60 years, however, physicians have noticed more "early-onset" cases in the past several years. Symptoms of the disease include resting tremor on one side of the body, generalized slowness of movement, stiffness of limbs and gait or balance problems.
Co-authors of the JAMA paper include Robert D. Abbott, Ph.D., Helen Petrovitch, M.D., David M. Morens, M.D., Andrew Grandinetti, Ph.D., Ko-Hui Tung, M.S., Caroline M. Tanner, M.D., Ph.D., Kamal H. Masaki, M.D., Patricia L. Blanchette, M.D., M.P.H, J. David Curb, M.D., M.P.H, Jordan Popper, M.D., and Lon R. White, M.D., M.P.H. Their work was supported by VA, the Department of the Army, National Institutes of Health, National Institute of Aging, and National Heart, Lung and Blood Institute.
VA research provides improved medical care for veterans, as well as the general population. Through its unique affiliation with medical schools, VA plays a crucial role in educating future physicians in research and clinically oriented areas.
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SPECIAL NOTE FOR REPORTERS: Dr. G. Webster Ross of the Honolulu VA Medical Center and lead author of the Parkinson Disease/Coffee Intake study, is available for press interviews. He can be reached at (808) 524-3595. For additional assistance, please contact Jim Blue at (212) 807-3429.
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