One in five Americans has significant hearing loss, far more than previously thought, according to new research that has scientists warning of an impending public health threat.
Researchers at the Johns Hopkins University say the growing number of seniors in the United States are at risk of isolation from their hearing loss and could suffer physical and mental debilitation.
"People think hearing loss is an inconsequential part of getting older," said Dr. Frank Lin, an assistant professor in Hopkins' department of otolaryngology-head and neck, who led the study. "But hearing loss is associated with a greater risk of developing dementia, and having poorer cognitive and physical functioning."
The World Health Organization says significant hearing loss is when someone is unable to hear sounds of 25 decibels or less. Lin says words sound mumbled, especially when there is background noise.
The study found that about 30 million Americans, or close to 13 percent of the population, had such loss in both ears and 48 million, or just over 20 percent, had loss in at least one ear. Previous estimates were closer to 21 million to 29 million.
This study, published in the Archives of Internal Medicine, used data from all ages and ethnicities collected in a continuing federal research program called the National Health and Nutritional Examination Surveys.
The data showed that the risk of hearing loss doubles in a person every decade, and because more people are living longer, there are now more people with hearing loss. Hearing loss is more prevalent in those with hypertension and diabetes, and among white men compared with women and African-Americans. The female hormone estrogen and melanin, which colors skin, seem to be protective, Lin said.
Hearing loss generally occurs when hair cells in the inner ear responsible for converting sound into signals that go to the brain die off over time and are not replaced. Damage isn't typically seen for years and losses aren't reversible, and the only preventive step for most people is to avoid long periods of loud noises. Lin suggested, for example, that young people avoid the speakers at concerts and stop using ear buds that cause them to listen to music more loudly.
Lin said only an estimated 20 percent seek treatment. Others don't recognize or acknowledge a problem, especially if the loss comes gradually. People hear some sounds and fill gaps by asking speakers to repeat themselves, turning up the television and reading lips and other signals.
That's what Bob Ward did. The 66-year-old Annapolis man believes his hearing loss results from military service in Vietnam. About 15 years ago, he went for hearing aids.
He's since been through several pairs of increasing strength. They took some getting used to because they don't filter background noise well, but he said they helped until recently. He was finding it hard to communicate at home and at work at Pitney Bowes, where he is a director of applied technology.
"I didn't notice at first, but my wife and family noticed that I'd become rather withdrawn," he said. "I wasn't participating because I couldn't hear and pretty soon people wouldn't even try and include me in conversation. It has a real psychological effect. I started to feel isolated."
Ward said he avoided coffee shops because he was afraid they'd ask him a question. He even began researching jobs he could do without hearing.
One day he was visiting his grandchildren's school in Washington, where about half the kids are deaf and have cochlear implants, surgically implanted electronic hearing devices for the more severely hearing impaired. He was inspired to head to Hopkins to see if would be a candidate.
And now that he's had one implant, he's begun to recognize long-ago familiar sounds, such as the clanking of his dogs' tags.
"I can have conversations that I wasn't having before," he said. "I see other people who can't hear and they give up on things. I see how it can become mentally and then physically debilitating."
And plenty of people admit to ignoring the problem. More than 60 percent of members of AARP reported difficulty hearing in noisy situations in a new poll by the group and the American Speech-Language-Hearing Association.
Yet only 43 percent have gone for a test even though hearing troubles have affected relationships for many. Close to two-thirds don't believe their problem warrants treatment, and about the same percentage say lack of insurance coverage and cost are reasons not to be treated. (Hearing aids cost $2,000 to $4,000.)
That frustrates Linda S. Remensnyder, an Illinois audiologist who has consulted with Lin and has become an advocate for the hearing-impaired. She says many of her older patients have become withdrawn and debilitated by the time they get to her.
She said some diseases and treatments cause hearing loss, along with age, but she believes the hearing loss makes their physical and mental health worse.
Remensnyder has joined other audiologists and the American Academy of Audiology, the Hearing Loss Association of America and AARP to encourage regular screenings, use of hearing aids and installation of hearing loops in public places such as theaters, shops and churches. The loops magnetically transmit sounds to a wireless receiver in hearing aids, filtering outside noise.
"Patients come in here and tell me that they've stopped going to activities," she said. "We not only have to provide hearing aids but make sure venues are audible. It's an incredible issue, and if we don't get it addressed we'll be paying for it. Maybe we can defer the onset of dementia."
Other scientists, including Dr. George Gates, a hearing expert at the University of Washington in Seattle, say they're not so sure hearing loss causes dementia. Gates says his research shows that dementia may cause hearing loss, and he is an advocate for more testing.
"What we've found is long before anyone gets a diagnosis of dementia, their ability to hear noise is severely affected, so a hearing test may reveal people at risk of dementia long before any other test," said Gates. He added that there is no cure for dementia, but early interventions may slow the progression.
He agreed with Lin that improving hearing can stave off depression, which he said can lead to other mental and physical maladies. "There absolutely is a public health threat from hearing loss," he said.
Lin, also an assistant professor in the epidemiology department in Hopkins' Bloomberg School of Public Health, plans to continue looking at the link to physical and mental health.
He's studying the cognitive abilities in those over 50 with hearing loss. He's also planning a larger study that will test the cognitive and physical abilities of people with hearing loss over years. One set will get free hearing aids, intensive instruction on using them and loop systems in some public areas. The other set will just be observed (they can buy a hearing aid themselves if they want).
"No one would think of not treating their high blood pressure, but hearing loss is still perceived as not that bad for you," Lin said. "If 30 million have hearing loss and less than one in five people do anything about it, and studies show that hearing loss is associated with adverse outcomes, think of how huge a public health threat that is."
meredith.cohn@baltsun.com
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Dr. Frank R. Lin, assistant professor in the Division of Otology, Neurotology and Skull Base Surgery at Johns Hopkins Medicine, is the lead researcher in the hearing study. (Kenneth K. Lam, Baltimore Sun)