Study Seeks Ways to Retard Hearing Loss
BEAVER DAM, Wis. -- Naturally, the last thing older folks in Beaver Dam want to hear is that they are going deaf. So 3,753 of them have agreed to regular testing and probing to help people everywhere learn some simple and unexpected things that may ward it off.
Gradual hearing impairment -- long shrugged off as just another inescapable indignity of aging -- is at last getting some serious study, and the results from Beaver Dam suggest that something can be done about it: having a drink, perhaps, or even just going for a walk.
Elderly hearing loss has a fancy name, presbycusis, but surprisingly little is known about what underlies it. Changing this is the goal of the Epidemiology of Hearing Loss Study, the country’s largest project devoted solely to the sources of this seemingly universal health problem.
“People need to know that hearing loss might not be an inevitable part of growing older,” said Karen Cruickshanks of the University of Wisconsin, the study’s director.
Since 1993, her team has measured the hearing and health of two-thirds of people over age 48 in Beaver Dam, population 15,000, a manufacturing city in the rolling dairy lands about 60 miles northwest of Milwaukee.
“This settles one thing,” said John Landdeck, 61, president of the community hospital and a study volunteer. “Everybody in town knows when they can’t hear their wife whether it’s their hearing or her mumbling.”
That, actually, is one of the study’s more interesting findings. It shows men have poorer hearing than women, even when a lifetime of noisy jobs and hobbies like chain sawing and snowmobiling are figured in. And as people get past retirement age, their hearing tends to get worse. Over age 80, about 90% of the population has trouble.
If Beaver Dam is typical -- and the researchers believe it is -- then hearing loss is considerably more common than experts would have guessed. The usual national estimate is that one-third of older Americans have some problem. This study puts the figure at nearly half.
But even if more whadya-say moments are hard to avoid, Cruickshanks hopes her study will find ways to delay the problem or keep it as mild as possible. Although the hazards of incessant loud noise are well-known, this study is beginning to show the effects of other less obvious health and living habits, including some people can change.
“It’s a very complicated subject,” said Dr. James Battey, director of the National Institute on Deafness and Other Communication Disorders. “A lot goes into it, and we are only beginning to sort it out.”
Such as drinking, for example. Beaver Dam people who have a drink or two a day are about 40% less likely than nondrinkers to have hearing loss, although heavy drinking is bad for hearing, just as it is for other partsof the body. Exercise also seems to prevent or delay elderly hearing loss.
On the other hand, smoking seems to be bad for the hearing. In Beaver Dam, smokers are about 70% more likely than nonsmokers to have some loss.
All of this raises the possibility that what’s good for the heart -- or bad for it -- may have similar effects on hearing. Clogged arteries are the underlying cause of heart attacks, and the researchers suspect that decreasing blood flow to the inner ear increases the risk of going deaf.
They found that heart attack survivors are almost twice as likely to have poorly working cochleas, the spiral-shaped organs in the ears that convert vibrations into nerve impulses. And those whose hearing worsened during the study tended to have more thickening of the carotid artery.
If preventing heart disease also saves hearing, it might offer another reason to take cholesterol-lowering drugs called statins. So researchers are watching the Beaver Dam residents who use the pills.
Still, none of this proves a real link between bad hearts and bad ears. Researchers outside the Beaver Dam project are divided on the subject.
“I think there absolutely is something there,” said Sandra Gordon-Salant, a University of Maryland hearing researcher. “Is it the cardiovascular disease that causes hearing loss? Is it the medications people take? That needs to be teased out.”
But Dr. George Gates, director of the Bloedel Hearing Research Center at the University of Washington, is skeptical. He analyzes data from the landmark Framingham Heart Study, the only other major U.S. project to measure hearing over time, and sees no strong link between hearing and hearts. Even if people with poor hearing really do have more heart disease, he says, it may simply be because people who hurt their hearing with noisy jobs are also likely to eat red meat and smoke.
While that debate plays out, the older folks of Beaver Dam cannot help being more aware of their hearing and what harms it.
Retired nurse Helen Glewen, 61, says that since joining the study, she has persuaded her husband to wear earplugs when he hunts. And she has changed her seat at the County Fair’s country music shows. “I used to take a lawn chair and sit as close as I could,” she said. “Now I sit way up in the bleachers.”
Certainly noise is the most obvious cause of bad hearing. Like other research, the Beaver Dam project documents the damage of frequent exposure, especially to anything above 85 to 90 decibels, such as the din once common in factories and foundries. People tend to have worse hearing later in life if they drove tractors without cabs, served in tanks in World War II or had any job where they needed to shout to be heard.
Hobbies may also contribute to deafness, especially if they involve guns. For instance, Beaver Dam target shooters are 50% more likely to have poor hearing; each five years of hunting results in a 7% hike in the likelihood of high-frequency hearing loss.
Among other loud hobbies, the worst seems to be woodworking. Men who putter in their shops have a 30% increase in hearing loss, probably because the saws are loud and they spend a lot of time at their task.
The researchers also asked about exposure to blenders, hair dryers, food processors and vacuum cleaners, although none caused any measurable harm.
Despite Glewen’s worry about country music, researchers conclude that concert-going is not much of a factor. However, some wonder what music is doing to younger people who are more interested in heavy metal than Hank Williams. For now, though, the research suggests that deafness will be less a problem for future generations.
Cruickshanks notes the youngest people in the study -- those in their late 40s and early 50s when they enrolled -- seem to lose their hearing less quickly than their elders, possibly because they have less ear-splitting jobs. “Certainly, there has been a big shift away from blue-collar jobs and a lot of improvements with noise reduction at work,” she noted.
But will too much head-banging rock cancel out the benefit of all that hushed desk work? Battey, for one, doubts it, unless the listener goes every night and sits in front of the speakers.
And headphones? Probably not either. “They may be annoying for other reasons, but not necessarily because they will compromise hearing, although I know there are parents all over the country who would like me to say that,” he said.
