A new survey of mostly middle-aged adults reveals that among people aged 45 to 54, one in nine shows signs of hearing impairment. And in the 55 to 64 age group, that number is one in four.
The researchers tested hearing in more than 2,800 adults between the ages of 21 to 84. Over that large range, 14%, or roughly one in seven, had lost some degree of hearing. As expected, the rate of hearing loss increased with age.
Almost all of those older than 80, about 90%, had lost some hearing, but the rate had already reached 11% among adults 45 to 54 years old, the largest age group in the study population.
Hearing loss "is a significant problem, even in middle age," said Dr Peter Rabinowitz of Yale University.
The authors, led by Scott Nash of the University of Wisconsin, classified subjects as hearing impaired if at least one ear had trouble hearing various sounds within the range of human speech.
The cut-off, Nash explained, is considered "mild impairment." These people may not even realise they have trouble hearing, said Dr Rabinowitz, since the changes can occur relatively slowly.
The authors found signs that hearing loss might be linked to risks for heart disease and stroke. Specifically, they saw hearing loss was correlated with the health of the blood vessels of the retina in the eye, an indication of blood vessel health overall.
Other studies have also linked ear health to heart disease and stroke risk, Dr Rabinowitz said in an interview. These findings "provide additional evidence" that such risk "may be associated with hearing."
The association makes sense, he noted that the inner ear depends on a rich supply of blood, and research shows that when blood circulation is compromised, the ear can suffer.
No relation to certain conditions
However, the authors did not see an association between hearing impairment and other measures of heart disease and stroke risk, such as hypertension, diabetes, and obesity.
"This may have been due to the younger age of the cohort, or the low prevalence of some of these conditions in this population," Nash suggested. "As this population ages, however, it will be very informative to see what effect, if any, these diseases have on future hearing."
At least 29 million Americans currently live with hearing impairment, most commonly men, older adults, and those exposed to loud noises, according to the paper published online in the Archives of Otolaryngology-Head & Neck Surgery.
To take a closer look at hearing loss in various age groups, Nash and his team studied 2,837 adults.
Indeed, the rate of hearing impairment increased with age, exceeding 40% in those 65 and older. But it also affected 6% of those between the ages of 35 and 44.
The findings are "unfortunately not all that surprising," Nash said.
Doctors typically do not routinely screen middle-aged adults for hearing loss. The US Preventive Services Task Force, sponsored by the US government's Agency for Healthcare Research and Quality, is in the midst of an evaluation of new evidence since 1996. That was when it issued its last recommendations, which are no longer available.
These findings suggest researchers should investigate whether it makes sense to do so, said Dr Rabinowitz.
(Reuters Health, Alison McCook, February 2011)