Study challenges old notion that menopause starts in the
ovariesSome of the most unpleasant symptoms of menopause,
such as hot flashes and night sweats, have long been
believed to originate in the ovaries.
But new research challenges that assumption, and instead
suggests that menopausal symptoms, at least in part, may
begin in the brain.
That's because the hypothalamus and the pituitary gland
stop reacting normally to estrogen in some women,
suggesting they may have developed a reduced sensitivity
to estrogen, researchers at the New Jersey Medical
School report in the Dec. 22/29 issue of the Journal of
the American Medical Association.
"This is an important new concept: Menopause doesn't
just originate in the ovary, but also in the brain,"
said Laura Goldsmith, a professor of obstetrics and
gynecology and women's health at the New Jersey Medical
School of the University of Medicine and Dentistry of
New Jersey.
These findings may lead the way to further research that
will ultimately help doctors predict the type of
menopausal transition a woman might have, and help to
design non-estrogen medications that could help reduce
symptoms that women experience as they enter this phase
of life, said Dr. Gerson Weiss, chairman of obstetrics
and gynecology and women's health at the New Jersey
Medical School.
Menopause refers to the time when menstruation stops. A
woman is not considered menopausal until she has not had
a period for 12 consecutive months, according to the
North American Menopausal Society. The time before
menopause, which is often rife with symptoms due to
hormonal fluctuations, is called perimenopause. During
perimenopause, common symptoms include hot flashes,
trouble sleeping, vaginal dryness, mood swings and
irregular periods.
This study stemmed from research done for the Study of
Women's Health Across the Nation (SWAN), which was
funded by the National Institutes of Health, that
examined women's' health as they approached menopause.
The SWAN study included more than 3,300 women between
the ages of 42 and 52 at the start of the study. A
subset group of 840 women provided daily urine samples,
which were tested for hormone levels. The samples were
collected daily for one full menstrual cycle or 50 days,
whichever came first.
From that group, the researchers learned that 160 did
not ovulate. After further analyzing the hormone levels
from the non-ovulating women, the researchers discovered
that these women fell into three distinct groups.
The first group had an increase in their levels of
estrogen, and then had an appropriate surge of
luteinizing hormone (LH) that should have triggered
ovulation, but didn't. According to Weiss, this lack of
response indicated a problem originating in the ovary.
In the second group, estrogen levels peaked, but there
was no correlating surge in LH, which Weiss said should
be triggered by the hypothalamus and pituitary gland
responding to higher estrogen levels.
The third group had similar estrogen levels early in
their cycles, but didn't have an increase in estrogen
later as the first and second groups did. LH levels
didn't surge, but were higher for most of the cycle than
they were in the other groups.
According to Weiss, this is "clear evidence that the
brain is not responding to hormones," suggesting the
second and third groups showed different kinds of
decreased sensitivity to estrogen in the brain.
The women in the third group were also the ones most
likely to report symptoms, such as hot flashes and night
sweats.
Goldsmith said the researchers hope to continue studying
these women. She said they'd especially like to learn
how the timing of menopause correlates with their
findings. For example, the researchers would like to see
if the women in the third group were, perhaps, further
along in the menopausal process.
"It appears that what's going on in menopause isn't only
ovarian," said Dr. Steven Goldstein, a professor of
obstetrics and gynecology at New York University School
of Medicine. "We thought the pituitary responded to
lower levels of estrogen, but there may be a lack of
sensitivity to estrogen in the hypothalamus and
pituitary."
What's important for women to know, said Goldsmith, is
that there are "real biochemical changes occurring
during menopause." Researchers are beginning to
understand how those changes start to occur, which is
the first step in trying to come up with more effective
treatments.
SOURCES: Gerson Weiss, M.D., professor and chairman,
obstetrics and gynecology and women's health; Laura
Goldsmith, Ph.D., professor, obstetrics and gynecology,
New Jersey Medical School, University of Medicine and
Dentistry of New Jersey, Newark; Steven Goldstein, M.D.,
professor , obstetrics and gynecology, and obstetrician/gynecologist,
New York University School of Medicine and Medical
Center, New York City; Dec. 22/29, 2004, Journal of the
American Medical Association
For more information visit:
http://www.menozac.com/?aid=829107
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