After Grandma died, Papa decided to live in a care facility. But over the past two years, he has gone downhill fast—he has few friends, it’s hard for him to hear the TV, he finds it frustrating to talk to family when they visit and even more so when they call on the phone. The director says this happens frequently and suggested checking his hearing. She is going to match him up with some outgoing types and thinks he should see the doctor about hearing aids or antidepressants.
Sensorineural hearing loss that occurs in older adults is called presbycusis. Loss of hearing due to the aging process is a growing issue because people are living longer and yesterday’s baby boomers have become today’s seniors. Presbycusis is already the most common neurodegenerative disorder and cause of communication difficulty in America.
Approximately 18 percent of middle-age adults (those forty-five to sixty-four years old) suffer from hearing loss compared to 30 percent of those sixty-five to seventy-four, and nearly 50 percent of those older than seventy-four. The degree and age of onset of presbycusis tend to be hereditary, and men are disproportionately affected. Age-related hearing loss has a great impact on the quality of life of tens of millions of older people and is closely associated with all forms of dementia.
Presbycusis is progressive and affects both ears. The degeneration of hair cells in the inner ear is the primary cause. Other parts of the cochlea along with the auditory nerve and brain are also affected by presbycusis.
It is usually not possible to distinguish the natural effects of aging from other factors such as a lifetime of noise exposure, incidents of head trauma, use of medications, and even a history of ear infections. Presbycusis begins by affecting hearing in the higher frequencies and remains more severe in those frequencies. This is significant because high-frequency tones are important in understanding spoken language. Although the cellular degeneration of presbycusis may begin as early as adolescence, it is slow to progress and usually is not a problem until the sixth decade. The age when presbycusis becomes noticeable often runs consistently within families, indicating a genetic component. Among the ironies of aging, men’s hearing tends to become worse at a time when women’s voices tend to become softer.
Symptoms of Presbycusis
Slowly progressive loss of hearing is unnoticeable at first. As it becomes worse, we tend to ignore it. At some point, usually in our sixties, presbycusis often becomes more annoying, a source of aggravation. Losing the ability to hear other people is first blamed on them, and we wonder why people mumble, speak so softly, talk to us from other rooms, or turn away when speaking. We try to accommodate to this change, along with many others of course, as part of life. But it’s not long before our hearing losses begin to irritate others more than ourselves. Old friends ask, why don’t you pay attention to what I say? New friends think we are dull or ignoring them.
People with presbycusis may also become withdrawn, and as loved ones and good friends pass away, it is hard to make new friends. This is especially true in the social activities at extended care facilities. Meals in large noisy dining halls and the bustle of group activities make hearing difficult for anyone. It becomes a serious effort to hear someone’s name much less remember it and have a conversation. With presbycusis, life tends to become smaller and smaller and personalities can involute unless something is done.
Another problem of presbycusis is loudness discomfort when listening. Presbycusis is associated with narrow dynamic range, the range of loudness between what is barely heard and what is too loud. A senior with presbycusis may ask a friend to speak up, then surprise her by saying, “You don’t have to yell at me!”
As mentioned, presbycusis is partly due to degeneration of the hearing centers in the brain. And hearing loss is frequently found in people with early stages of dementia, also called mild cognitive impairment. It is thought that speech signals become difficult for the brain to process. Speech testing may show a disproportionate loss of understanding compared to threshold levels. In these instances, tests of central auditory processing (see chapter 26), the brain’s ability to deal with nerve signals, is evaluated.
It can also be valuable to test central processing when older adults who seem to be ideal candidates for hearing aids instead find the aids make sound louder but not clearer. The reason may not be the hearing aid or even the ear, but rather the brain’s ability to process input.
Causes of Presbycusis
Aging changes the cochlea microscopically in four known ways: loss of hair cells and their supporting cells; loss of auditory nerve cells (that carry signals to the brain); degeneration of the stria vascularis (part of the cochlea that maintains chemical and bioelectric balance); and thickening of the basilar membrane (which normally vibrates freely).
One of the rare causes of presbycusis is mutation of a mitochondrial gene (see chapter 6). The abnormal gene is passed from mothers to each of her children. It causes hearing loss by affecting the oxygen supply of the inner ear, increasing the rate of programmed cell death (apoptosis) as well as anatomical changes. Two specific inherited DNA deletions have been identified.
Coping with Presbycusis
At the time of writing, there is no cure for presbycusis or any type of nerve deafness. Chapter 30 introduces regenerative medicine in otology, but that approach is currently in the domain of basic and clinical research—not clinical practice.
Beware of claims made by some makers of ear pills, especially if they are called dietary supplements and thereby are not regulated and do not require their claims to be proven. If a pill could really reverse or prevent hearing loss, the inventor would likely be a Nobel Prize winner.
The first step in dealing with presbycusis is to recognize the problem and see an ear specialist. One of the most common disorders mistaken for presbycusis is a wax impaction that is easily removed at the time of your visit to the doctor. Other treatable causes of hearing loss in older adults should also be ruled out before the diagnosis of presbycusis is made. These include disorders of the outer, middle, and inner ears as well as certain brain tumors. Hearing aids are the primary treatment for presbycusis and cochlear implants are effective when indicated.
There are also many accommodations that can be made to enhance communication with mild to moderate presbycusis. Imagine a conversation of an older married couple:
“Can’t you stop mumbling all the time?”
“You never did pay attention to what I say.”
“Then don’t talk to me when I’m in the other room.”
“Then put down the newspaper when I have something to say.”
“And get your head out of the refrigerator when you say it.”
“And turn down the TV so you can hear me.”
“And you need to find a nice quiet restaurant if you want dinner.”
Most people with presbycusis can communicate well when they control the surrounding noise. For an important conversation, sit facing each other in a well-lit quiet room no more than six feet apart. Speak up but do not exaggerate your words, rush them, or make them too loud. Reading each other’s expressions, hand gestures, and natural lip reading are all helpful. Turn off any machines that make noise, including the TV, stereo, and kitchen appliances. Put away books, newspapers, and other distracting items. In a restaurant, sit with your back to the room so your head blocks some of the noise from reaching your ears. Ask your dinner partner to sit in the corner. This will focus the sound into the corner where your dinner partner is sitting causing him or her to speak louder. Your attention is concentrated into the corner, but theirs is distracted by the people walking by.
What to Expect
As we age, hearing loss continues slowly to get worse, about 1 dB per year. As hearing loss progresses, we need to re-program our hearing aids and eventually get new ones. It is also important to avoid noise exposure, have good control of diabetes if present, and avoid ototoxic medications. The most effective treatment for mild cognitive impairment and memory loss is a healthy diet and exercise. This is more important than ear pills or mind training games.