Caffeine, Estrogen Linked To Parkinson's
Women who drink
a lot of coffee each day -- more than six cups worth -- and who are receiving
hormone replacement therapy appear to have an increased risk of developing
Parkinson's disease, researchers reported.
The risk is
four times that of women who take hormones after menopause but do not drink
a lot of coffee, said Dr. Alberto B. Ascherio, associate professor of medicine
at the Harvard School of Public Health/Brigham and Women's Hospital in
Boston.
Dr. Ascherio
noted numerous studies have demonstrated caffeine intake among men is associated
with a reduced risk of Parkinson's, but for women who drink coffee and
other caffeine-laden drinks the relationship has not been established.
"What is interesting
about this study is that there could be a relationship between caffeine
and estrogen and Parkinson's Disease," said Dr. C. Warren Olanow, professor
and chairman of the department of neurology at Mt. Sinai School of Medicine.
He said many studies have suggested caffeine and estrogen are associated
with reduced risk of neurological disorders such as Parkinson's.
"To find that
hormones and caffeine increase the risk is really a foreign idea," he told
attendees at the annual meeting of the American Neurological Association.
Dr. Ascherio
scrutinized data accumulated through the Nurses Health Study, in which
dietary and health information was collected on 77,713 women. The women
were studied for 18 years. Within that group, the researchers were able
to find 154 cases of Parkinson's disease.
Although he
determined that the combination of heavy caffeine consumption and hormone
therapy was associated with an increased risk of Parkinson's among women,
Dr. Ascherio said the data also suggested hormone therapy and low or absent
caffeine consumption was associated with a reduced Parkinson's risk.
"These results
suggest that hormone use modifies the effect of caffeine on the risk of
Parkinson's disease," he said.
Dr. Olanow
said the study appears to "support a relationship and adds confusion to
the issue.
Nevertheless,
the work warrants further investigation."
He said sorting
out the thousands of variables that could be involved in determining what
might cause Parkinson's is a complex task.
"However, it
is easy to be off base," he told United Press International.
Dr. Ascherio
suggested when researchers work on the relationship between caffeine and
Parkinson's the interaction between the them "should be taken into account
in the interpretation of epidemiological studies and particularly in the
design of clinical trials of caffeine or estrogen."
Among men,
he said, "most studies are convincing that men who drink caffeine have
a lower risk of Parkinson's Disease. Of course, we don't know why."
Some research
suggests in women estrogen-type hormones and caffeine both are metabolized
through a similar pathway, which might explain some of the caffeine-estrogen
story, Dr. Ascherio said.
Overall, he
noted, hormone use did not have any association with Parkinson's Disease
when compared with women who never used hormones. Only when the relationship
between Parkinson's disease and coffee consumption did Ascherio find differences.
He did not see any major differences between no caffeine use and low caffeine
use -- only among those women with high caffeine consumption.
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