HONOLULU, April 24 – A new study shows an association between cardiovascular disease and age-related hearing loss – particularly in women who’ve had a heart attack, researchers report today at the American Heart Association’s Asia Pacific Scientific Forum.
“These findings seem to support previous research that found a link between cardiovascular disease, its risk factors (such as cigarette smoking) and age-related hearing loss,” says lead author Peter Torre III, Ph.D., post-doctoral fellow, department of population health sciences, University of Wisconsin Medical School.
As part of the Epidemiology of Hearing Loss Study (EHLS) in Beaver Dam, Wisconsin – a population-based study that investigated hearing loss in older people – cochlear function was tested in about 1,600 study participants ages 52 to 97. Forty-one percent were male.
The cochlea is a spiral-shaped organ in the inner ear that contains inner and outer hair cells, the sensory cells responsible for hearing.
In addition to the cochlear function test, study participants answered interview questions about their history of cardiovascular disease (CVD). Researchers controlled for age, gender and noise exposure on the job and during leisure activities.
They found that participants with a history of CVD were on average 54 percent more likely to have impaired cochlear function than adults without CVD. People who exercised at least once per week were on average 32 percent less likely than sedentary individuals to have impaired cochlear function.
Study participants with a history of heart attack were 80 percent more likely to have impaired cochlear function than those who had not had a heart attack. This was particularly evident in women, says Torre.
Women with a history of heart attack were 2.7 times more likely to have impaired cochlear function than women who had not reported a previous heart attack. However, a history of heart attack was not associated with cochlear function in men.
Researchers tested cochlear function with distortion product otoacoustic emission equipment, which evaluates how well the outer hair cells are working. This test of cochlear function was developed to supplement, not replace, standard hearing testing. The test measures how outer hair cells respond to sounds from low to high pitch. It is particularly accurate at higher frequencies, where hearing loss occurs more often.
“This is a new technology that measures the responses of the outer hair cells to sounds. When the outer hair cells don’t respond normally to a sound, that indicates a possible hearing loss,” Torre says. One caveat is the variability associated with cochlear response. He says there is a chance that an ear with normal hearing may not produce a response, but the technology is sufficiently accurate and is used to screen newborns for hearing loss and to monitor subtle effects of medications.
“We can’t explain the gender differences that were uncovered during this study, but we hope that a follow-up study may shed more light on this,” Torre says. “It’s possible that the apparent strong, cross-sectional association between heart attack and cochlear function in women could have something to do with hormonal influences, but further research is needed to know for sure.
The study also found that a self-reported history of stroke or angina was not associated with the results of the cochlear function test.
Torre says this cross-sectional study provides preliminary evidence of an association between cardiovascular disease and abnormal cochlear function, particularly for women with a history of heart attack.
However, he cautions against jumping to conclusions about any possible cause-and-effect relationship between age-related hearing loss and CVD based on these preliminary data. “Cochlear function and cardiovascular disease were measured at one point in time and we don’t know which came first,” he says, and adds that further, longitudinal research is needed.
In addition to the interviewer-assisted questionnaire and the cochlear function test, study participants underwent carotid artery scans to measure atherosclerosis. “We are analyzing these scans to determine if mild atherosclerosis is associated with cochlear function test results,” Torre says.
Co-authors are Karen J. Cruickshanks, Ph.D.; David M. Nondahl, M.S.; Terry Wiley, Ph.D.; and Michael P. Gorga, Ph.D.
CONTACT:
Darcy Spitz or Carole Bullock
AHA News Media Relations
Hawaii Convention Center
Honolulu, Hawaii
Ph. 808-792-6515
Abstract P87