High Blood Levels Of Urate Linked To Lower Risk Of Parkinson's Disease
Updated: 6/21/2007 12:06:40 PM
Science Daily - In a new, large-scale, prospective study exploring the link
between levels of urate in the blood and risk of Parkinson's disease,
researchers from the Harvard School of Public Health (HSPH) have found that
high levels of urate are strongly associated with a reduced risk of the
disease.

Urate is a normal component of blood, and although high levels can lead to
gout, urate might also have beneficial effects because it is a potent
antioxidant. Parkinson's disease is a chronic, progressive nerve disorder
associated with destruction of brain cells producing dopamine, a
neurotransmitter essential to the normal functioning of the central nervous
system.
"This is the strongest evidence to date that urate may protect against
Parkinson's disease," said lead author Marc Weisskopf, Assistant Professor
of Environmental and Occupational Epidemiology at HSPH.
The researchers used the HSPH-based Health Professionals Follow-up Study, a
population of male health professionals established in 1986, as the source
for their data. The study cohort included more than 18,000 men without
Parkinson's disease who had provided blood samples between 1993 and 1995 and
whose subsequent health status was followed.
The researchers found that men in the top quartile of blood urate
concentration had 55 percent lower risk of developing Parkinson's disease
than men in the bottom quartile. This difference was not explained by
differences in age or other risk factors for Parkinson's disease. The
results of two previous studies had suggested a possible inverse relation
between blood urate and risk of  Parkinson's disease, but it is only when
the previous data were combined with those of this new study that the
evidence became compelling.
The authors hypothesize that urate's antioxidant properties may help dampen
the effects of oxidative stress, which appears to contribute to the
progressive loss of the dopamine-producing brain cells that occurs in
individuals with Parkinson's disease. If so, elevating blood urate could be
helpful for patients with Parkinson's disease, said Alberto Ascherio,
Associate Professor of Nutrition and Epidemiology at HSPH and senior author
of the study. To follow-up on this clue, Ascherio, along with co-author
Michael Schwarzschild, a movement disorder specialist at Massachusetts
General Hospital, and colleagues at the Parkinson Study Group, a
collaborative group of Parkinson's disease researchers from the U.S. and
Canada, accessed the databases of two large, randomized studies conducted
among patients with early Parkinson's disease. The preliminary results,
presented in abstract form at recent meetings, showed a slower progression
of the disease among individuals with high blood urate.
"It is still uncertain whether urate exerts a neuroprotective effect, but
approaches to elevating urate levels are nonetheless worth considering as a
potential neuroprotective strategy," said Ascherio, who is now collaborating
with Schwarzschild and others in the design of a clinical trial in
individuals with Parkinson's disease to examine this possibility. "But
elevating blood urate increases the risk of kidney stones and may have
adverse cardiovascular effects and should only be attempted in the context
of a closely monitored randomized trial until beneficial effects are
proven," he added.
The study was supported by National Institutes of Health/National Institute
of Neurological Disorders and Stroke, the Kinetics Foundation and the
Intramural Research Program of the National Institutes of Health/National
Institute of Environmental Health Sciences.
The findings were published in The American Journal of Epidemiology. "Plasma
Urate and Risk of Parkinson's Disease," M. G. Weisskopf, E. O'Reilly, H.
Chen, M. A. Schwarzschild and A. Ascherio, American Journal of Epidemiology,
published online June 20, 2007.
Note: This story has been adapted from a news release issued by Harvard
School of Public Health.

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© 2007 Science Daily

Rayilyn Brown
Board Member AZNPF
Arizona Chapter National Parkinson's Foundation
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