Two new studies show that hormone therapy for women is linked to
brain shrinkage, but not to the small brain lesions that are the first
sign of cerebrovascular disease. The studies are published in the
January 13, 2009, print issue of
Neurology®, the medical journal of the American Academy of Neurology.
Earlier
studies showed that estrogen with or without added progestin increased
the risk for developing dementia and cognitive decline, or difficulty
with thinking skills and memory in women age 65 and older.
These
new studies aimed to look at how the hormones might affect memory and
thinking skills. The studies involved participants of the Women’s
Health Initiative hormone therapy clinical trials who also agreed to
participate in a substudy called the Women’s Health Initiative Memory
Study. These studies were stopped earlier than planned when researchers
found that the hormone therapy increased health risks and failed to
prevent heart disease.
Researchers took MRI brain scans of 1,400
women ages 71 to 89 one to four years after the Women’s Health
Initiative hormone studies ended. They found women who had taken
estrogen with or without progestin had smaller brain volumes in two
areas of the brain than the women who had taken a placebo. Brain volume
was 2.37 cubic centimeters lower in the frontal lobe in the women
taking estrogen and .10 cubic centimeters lower in the hippocampus.
Both areas are involved in thinking and memory skills, and loss of
volume in the hippocampus is a risk factor for dementia.
“These
effects were most apparent in women who may already have had some
memory problems before they started taking hormones,” said study author
Susan Resnick, PhD, of the National Institute on Aging in Baltimore,
MD. “This suggests that estrogen may adversely affect thinking skills
among women whose brains may already be beginning a neurodegenerative
disease process.”
In the second study, researchers found that
hormone therapy was not linked to an increase in volumes of small
vascular lesions in the brain or “silent strokes” that are often the
first sign of cerebrovascular disease. “This was not what we expected
to find,” said study author Laura H. Coker, PhD, of Wake Forest
University Health Sciences in Winston-Salem, NC. Coker said the
negative effects of hormone therapy on cognitive skills may not be
related primarily to vascular disease but to neurodegeneration, which
is supported by the first study’s findings of brain atrophy.
The
Women’s Health Initiative, a major 15-year research program designed to
address the most frequent causes of death, disability and poor quality
of life in postmenopausal women, is funded by the National Heart, Lung,
and Blood Institute. The memory study was also funded in part by Wyeth
Pharmaceuticals, Inc.
The American Academy of Neurology, an
association of more than 21,000 neurologists and neuroscience
professionals, is dedicated to improving patient care through education
and research. A neurologist is a doctor with specialized training in
diagnosing, treating and managing disorders of the brain and nervous
system such as multiple sclerosis, restless legs syndrome, Alzheimer’s
disease, narcolepsy, and stroke.
For more information about the American Academy of Neurology, visit www.aan.com.
