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Doctor's Guide to the Internet: Medical & Other News
ICPDMD: Estrogen Beneficial As Parkinson's Treatment
NEW YORK, NY-Oct. 13, 1998 -- New research suggests hormone replacement
therapy may help prevent the onset of Parkinson's disease, as well as
alleviate some of the symptoms of the devastating disorder.
The preliminary findings of four studies on the estrogen/Parkinson's
disease connection were presented here today at the fifth International
Congress of Parkinson's Disease and Movement Disorders.
"Perhaps estrogen holds the key to why women develop Parkinson's
disease less often and are at a lower risk for it than men," said
Demetrius Maraganore, M.D., associate professor of neurology at Mayo
Clinic and Mayo Foundation, Rochester, MN.
In a preliminary study, Dr. Maraganore and fellow researchers found
postmenopausal women on hormone replacement therapy (HRT) were less
likely to have Parkinson's disease than those who were not on the
therapy, suggesting estrogen may help protect against development of the
disease.
The interest in the estrogen/Parkinson's connection has been piqued
by research in recent years showing estrogen may be a protective factor
in Alzheimer's disease, a neurological disorder that has many
similarities to Parkinson's.
In related studies:
· Postmenopausal women with Parkinson's Disease who had taken HRT scored
16 percent higher on long-term verbal memory tests than those who had not
had HRT, according to a study conducted at the University of Utah School
of Medicine.
· National Institutes of Health (NIH) researchers found that the estrogen
in hormone replacement therapy may actually increase absorption of the
Parkinson's disease drug therapy levodopa, in contrast to previously
accepted thought that HRT interfered with absorption of the drug.
· Higher levels of naturally occurring estrogen may protect some people
from Parkinson's disease, a University of Miami study suggests.
"All these studies are scratching at the surface, but they begin to paint
a picture of the benefits of estrogen on Parkinson's disease," said Lisa
Shulman, M.D., assistant professor of neurology at the University of
Miami School of Medicine.
Six (eight percent) of 72 postmenopausal women with Parkinson's disease
had been on HRT for six months or more, versus 10 (14 percent) of 72
women with no Parkinson's Disease, according to the Mayo Clinic study.
Ranging in age at menopause from 30 to 56 and located through the
Rochester Epidemiology Records Linkage system, each of the 72
postmenopausal women with Parkinson's disease were individually age
matched with 72 postmenopausal women who did not have Parkinson's.
Researchers then compared the numbers in each group who
had been on HRT for different lengths of time.
"No matter how we defined estrogen use, it was less common in
Parkinson's disease patients than in the control group," Dr. Maraganore
said. "The next step is to do a large, multicentre study, but we
definitely see a trend."
Mayo researchers also found that women with Parkinson's disease were
three times more likely to have had hysterectomies than women who did not
have the disorder, suggesting that the loss of naturally occurring
estrogen is a risk factor. Although not all of the women who had
hysterectomies had their ovaries removed, the surgery is often warranted
when those organs do not function normally or produce estrogen, resulting
in uterine dysfunction, note researchers.
In another study, 12 women with Parkinson's disease who were on or had
been on postmenopausal hormone replacement therapy scored an average of
16 percent higher on long-term verbal memory tests than nine women who
had not been on HRT, according to University of Utah researchers.
"Our research suggests hormone replacement therapy may benefit verbal
long-term memory, without necessarily affecting other Parkinson's
symptoms adversely," said Perla Thulin, M.D., assistant professor of
neurology at the University of Utah School of Medicine, Salt Lake City.
"Estrogen has been reported to enhance verbal memory in healthy
postmenopausal women, so the beneficial effect may not be specific to
Parkinson's, but could be particularly helpful for those with a disease
that can affect memory."
The 21 postmenopausal women with Parkinson's disease were subjected to
a four-hour battery of tests that measured arm and hand speed and
dexterity, as well as short- term and long- term verbal memory, auditory
attention, visual-spatial skills and global cognitive function. An
improvement in verbal long-term memory among patients on HRT was the only
significant difference noted between the groups.
Nine of the women were on HRT at the time of the test, while three had
been on it for years but no longer were. Both groups seemed to benefit
from HRT, noted Dr. Thulin.
Contrary to anecdotal evidence in medical literature, an NIH study
found that HRT may actually improve the benefit associated with levodopa,
the standard Parkinson's disease drug therapy, rather than decrease its
effectiveness. Researchers say HRT potentially may allow patients to use
less of the drug, which has a number of side effects.
Levodopa is given to patients with Parkinson's to help them combat the
disabling symptoms of the disease, including stiffness, tremor and slow
movements. According to anecdotal evidence, some women with Parkinson's
disease who went on oral HRT and who were also taking levodopa had
noticed an increase in their symptoms.
In the double-blind, controlled NIH study, none of the eight women
with Parkinson's disease who were given an estrogen patch noted a
difference in the effectiveness of levodopa when given the drug
intravenously. In fact, researchers found that five of the women required
an average of 27 percent less levodopa to turn off their Parkinson's
symptoms.
"At home, levodopa is taken in pill form, rather than intravenously, so
we don't know whether these women will generally be able to take less of
the oral medication," said lead investigator Pierre Blanchet, M.D.,
formerly with the NIH and currently assistant professor of neurology of
the University of Montreal Medical School in Quebec. "But perhaps it is
possible to decrease the dosage. Decreasing the dosage may reduce the
incidence of sudden jerky movements, called dyskinesia, experienced by
many people who have been on levodopa for a while."
The women served as their own controls, each of them on an estrogen
patch for two weeks and a placebo for two weeks, with two weeks off in
between. The women also kept diaries to report their symptoms.
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