By Penny Stern, MD, MPH
NEW YORK, Jun 28 (Reuters Health) - Do women on estrogen replacement therapy
really fare better in terms of brain aging? A new study reported in a special
issue of the Neurobiology of Aging suggests that the answer is yes.
"This is the first study comparing brain aging in women who receive estrogen
to women who do not receive estrogen and our data demonstrate an important
difference in brain aging between the two groups," lead author Dr. Pauline Maki
tells Reuters Health.
Maki and her colleague Dr. Susan Resnick, are researchers at the Laboratory
of Personality and Cognition at the National Institute on Aging, part of the
National Institutes of Health in Bethesda, Maryland.
They used a special imaging technique called positron emission tomography
(PET), to evaluate how blood flow to certain areas of the brain change over time
in postmenopausal women taking estrogen compared with women not taking the
hormone.
"Over a 2-year interval, women who receive estrogen show more blood flow to
the hippocampus, a region of the brain that is implicated in Alzheimer's disease
and that is involved in memory formation," Maki explains.
"People who go on to develop Alzheimer's disease and people who are at
increased genetic risk for developing the disease show the opposite pattern:
decreased blood flow in the hippocampus," she adds.
The researchers obtained three measurements for each of the 28 study
participants, of whom 12 were on estrogen and 16 were not. A baseline PET scan
was taken while the women were not engaged in any task; two other scans were
done while the women were performing two different memory tasks.
Study participants were also asked to complete a range of additional tests,
Maki and Resnick explain. "Across a battery of standardized neuropsychological
tests of memory, (estrogen) users obtained higher scores than did nonusers of
comparable intellect," they write.
Maki does point out, however, that it's possible "the two groups might have
differed in important ways that we were not able to measure." For example, she
notes, the women on estrogen made the choice to take the hormone. "Studies show
that women who choose to take estrogen are healthier than women who do not and
see their doctors more often," Maki explains, adding that "it may be the
characteristics of women who choose to receive estrogen and not the biological
effect of the estrogen that affects risk for Alzheimer's disease."
Maki and her colleagues are continuing to explore the issue of brain aging
in the context of hormone replacement therapy. They have recently enrolled 2,900
women in a long-term study "to see whether hormones affect memory and other
mental abilities as women age."
