Hearing loss can lead to social isolation—and may be linked to dementia.
by Lisa James
Did your mom spend your teenage years shouting “turn that thing down!” whenever you cranked up your tunes? Were you always in front of the amplifiers every time the big acts came to rock your local arena?
As much fun as you had then, your overly sonic youth may explain why you have a hard time following conversations today.
“The one thing that’s been different for the Baby Boomers are all the years of amplified music that the generations before them did not have,” says John Burkey, MA, director of audiology at the Lippy Group for Ear, Nose and Throat in Warren, Ohio, and author of Baby Boomers and Hearing Loss (Rutgers University Press). He says a third of people age 65 and older have some degree of hearing loss.
Having to ask others to speak up is bad enough. What’s more troubling is a potential association between hearing loss and cognition problems, a link forged in the complex interplay between the ear and the brain.
Whether it’s the shriek of a Fender Stratocaster or the squeal of a baby, all sound causes the eardrum to vibrate. Vibrations then pass through the middle ear and into the cochlea, a snail-shaped organ that forms part of the inner ear. The cochlea is lined with hair cells, which generate nerve impulses that travel along the auditory nerve to the brain, where the primary auditory cortex interprets them.
Problems anywhere along this chain of transmission can impair hearing. Conductive hearing loss includes anything that blocks sound from reaching the inner ear: excess earwax, eardrum rupture, middle ear infection. Central hearing loss results from nerve or brain damage, such as that caused by stroke, trauma or tumors.
The type of hearing loss most often associated with aging is sensorineural, in which the inner ear becomes damaged. Over time, “the cochlea can’t transmit speech to the brain with sufficient fidelity, so the brain can’t understand what is being said,” says Frank Lin, MD, PhD, of the Johns Hopkins Center on Aging and Health in Baltimore.
Hearing and Thinking
Lin and his colleagues at the National Institute on Aging found that in people over 60 years of age hearing loss is linked to dementia risk (Archives of Neurology 2/11). One possible reason for this association is that the need to balance hearing and cognition puts the brain into overload. “For example, someone might spend the night trying to understand conversation at a restaurant and come home exhausted from the effort,” Lin says.
Another factor “is that hearing loss is known to lead to social isolation and loneliness, and Alzheimer’s disease has been linked to social isolation,” says Lin. Burkey agrees, saying, “The expectation that you can hear is ingrained. People begin to withdraw because communication is so much of an effort that it’s easier to stay at home.”
Lin says the most intuitive reason is that there is some common pathology linking dementia and hearing loss, “although we actually don’t think this is the case.” Scientists do know that cardiovascular disease risk factors such as high blood pressure have been associated with risk for both conditions.
Loud sound can damage the hair cells. “Everyone knows about industrial noise and loud music. But there’s also noise from lawnmowers, leaf blowers and string trimmers, all those power tools we use every week. Some vacuums are loud enough to be damaging,” says Burkey. Sound intensity is measured in decibels (dB). A lawnmower registers at 90 dB (the point at which hearing damage begins), a rock concert at 115 dB and a jet engine at 140 dB.
Other auditory risk factors include genetics, gender (men are more likely to be affected) and certain medications. Melanin—the substance responsible for skin color—seems to offer some protection, leaving lighter-skinned people more susceptible to hearing loss.
Hearing loss is easier to prevent than to treat. “You have a certain number of hair cells in the inner ear. Once you lose them, that’s it,” says Michael Seidman, MD, FACS, director of otologic/neurotologic surgery for Henry Ford Health Systems in Michigan and author of Save Your Hearing Now (Warner Wellness). Wear ear protection at loud events or when working with power tools. If you suspect your ears aren’t what they used to be, go for a hearing test. (You can find an audiologist through the American Academy of Audiology: www.audiology.org, 800-222-2336.)
Properly adjusted hearing aids can help but many people refuse to wear them. “The mantra is, ‘I’m not old enough for hearing aids.’ They think the aids would be much worse than the hearing loss, and the opposite is true,” says Burkey. One study found that only 14% of older adults with hearing loss used aids (Archives of Otolaryngology 10/03). Profound deafness may be treated with cochlear implants designed to help compensate for the loss of hair cells.
Because of the connection between cardiovascular problems and hearing loss, “whatever a person can do to live a healthier lifestyle would be helpful. It’s the old thing about diet and exercise,” Burkey says. Seidman favors the Mediterranean diet, which emphasizes such lean proteins as eggs and fish, fresh produce, nuts and olive oil. Avoiding tobacco is also crucial; exposure to second-hand smoke has been linked to hearing loss in adolescents (Archives of Otolaryngology 7/11).
Seidman says taking a good multivitamin can help protect the hearing mechanism against cell-damaging molecules called free radicals, generated when blood vessels feeding the ear narrow and widen in response to noise. A study in the Journal of Nutrition, Health and Aging found a 47% drop in risk among people whose diets include high levels of vitamin A; vitamin E was also found to be helpful.
Seidman has suggested taking several specific supplements in combination to his patients, adding, “A number of them stopped losing their hearing—they were losing 10 to 15 decibels a year.” The nutrients Seidman recommends include the B-complex of vitamins, which support healthy nerve function; the mineral zinc, which is concentrated in the cochlea; the antioxidants alpha-lipoic acid, quercetin and resveratrol; another antioxidant, glutathione, that retards cellular damage caused by pollutants; NAC, a detoxifying agent that Seidman says has been shown to help repair hair cells; acetyl-carnitine and coenzyme Q10, which help protect cellular energy-generating structures called mitochondria; and lecithin, which helps protect cell membranes.
Other nutrients may also help you maintain hearing as you age. Omega-3 fatty acids, such as those found in fish oil, “could prevent or delay the development of age-related hearing loss,” say scientists at the University of Sidney in Australia (American Journal of Clinical Nutrition 8/10). Noni, a Southeast Asian fruit with anti-inflammatory properties, has shown an ability to fight sensorineural hearing loss (Journal of Alternative and Complementary Medicine 10/04). And forestalling upper respiratory infections can help prevent middle-ear problems; a beneficial probiotic microbe called S. salivarius K12 produces proteins that help target infectious micro-organisms.
No matter what kind of music you favored in your youth, protecting your ears now may help protect your brain as well. “The majority of people consider hearing loss a consequence of aging,” says Lin. “There’s no understanding that hearing loss really has functional effects and dementia may be one of them.”