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Hormone replacement therapy (HRT) has been widely used for many years to relieve the symptoms of menopause, such as night sweats and hot flashes. But recent studies have shown its risks may outweigh its benefits.
In a pilot study, researchers from the International Center for Hearing and Speech Research at the University of Rochester and the National Technical Institute for the Deaf at the Rochester Institute of Technology found that older women receiving HRT did 10 percent to 30 percent worse on hearing tests than women not receiving HRT.
The researchers presented their findings Feb. 24 at the Association for Research in Otolaryngology's annual meeting in Daytona, Fla.
"We were surprised by the finding," says lead researcher Robert Frisina, a professor of otolaryngology at the University of Rochester Medical Center. "We thought hearing would be improved for the women in the HRT group."
The research team used three tests to compare the hearing of 32 women between the ages of 60 and 86 who had had HRT with 32 women of similar age who had not.
Among the women who had not received HRT, the researchers took into account normal age-related hearing loss when giving and evaluating the tests.
Two of the tests evaluated how the ear processes sound, and the other test evaluated how the brain processes sound, Frisina says.
Hearing loss among the women in the HRT group was most noticeable when background noise made understanding sentences difficult, such as in a crowd or at a party.
Women on HRT did poorly on all three tests, but it was on the test that evaluated how the brain processes hearing that women receiving HRT did the worst. Women in this group on average were 30 percent less effective in prioritizing and organizing sound, the researchers found.
Frisina speculates the hearing loss was caused either by the high dose of HRT given or the combination of estrogen and progesterone. "HRT apparently hurts the auditory system rather than helping it," he says.
There are correlations between loss of hearing and the loss of cognitive ability and dementia, Frisina notes. He adds the doses of estrogen in HRT may damage the estrogen receptors in the ear, which can also result in hearing loss.
"If HRT is going to continue to be used on a widespread basis, there needs to be a more extensive follow-up study to confirm that HRT is not helping but actually hurting hearing," Frisina says.
Frisina's team is continuing its research, using mice to try to identify exactly what causes HRT-related hearing loss.
The risks of HRT may outweigh its benefits, Frisina says. "Women really need to ask their doctor about starting or continuing HRT. And hearing loss needs to be added to the list of negative side effects," he says.
Dr. Sandra L. McFadden, an associate professor at the Center for Hearing and Deafness at the State University of New York at Buffalo, says she "questions the validity of the study."
Despite the efforts to carefully match the two groups of women, "there may be important differences among the women comprising the two groups that account for the results, rather than the influence of HRT," she says.
McFadden adds that based on her experimental studies of hormonal treatment in chinchillas, "estrogen treatment has no effect on basic hearing sensitivity, but it can influence susceptibility to noise-induced hearing loss."
"Before I would be willing to put much stock in this study's findings, I would want to see them replicated," she says.
The research comes on the heels of yet another damning study on HRT, this one finding that postmenopausal women who took HRT are at a higher risk of developing asthma. The study, appearing in the Feb. 23 issue of the Archives of Internal Medicine, says women on HRT were 2.29 times as likely to develop the breathing disorder as were women not on it.
SOURCES: Robert D. Frisina, Ph.D., professor, otolaryngology, University of Rochester Medical Center, Rochester, N.Y.; Sandra L. McFadden, Ph.D., research associate professor, Center for Hearing and Deafness, State University of New York, Buffalo; Feb. 24, 2004, presentation, Association for Research in Otolaryngology, annual meeting, Daytona, Fla.
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