The ‘baby boom’ generation is aging. In 2009, people over 65 represented 12.9% of the population, but by 2030, they will be 19.3%. From the Administration on Aging, the number of Americans over 65 is expected to double between 2008 and 2030, to around 72 million.
The figure (bottom) displays the American population by age and sex in 2012, and the forecast population in 2035, and 2060. This figure clearly shows the baby boomer population increasing and advancing in age throughout the period…and the trailing, but burgeoning Millennials.
Why should we be concerned? Because Hearing loss is the third most common chronic health condition among older adults! According to the National Institute on Deafness and Other Communication Disorders, hearing loss increases with age. Approximately one third of Americans between 65 and 74 and nearly half of those over 75 have hearing and communication problems.
What is Age-related Hearing Loss (ARHL)? ARHL is a gradual and progressive hearing loss that affects most people as they age. Due to the slow progression, adults with ARHL may not realize that their hearing and communication abilities are declining, or they may accept it as a normal part of aging.
Are there consequences? ARHL can cause serious problems. It diminishes communication, reduces functional independence, and increases the threat of cognitive disorders like dementia.
If you have ARHL, sounds may seem less clear and lower in volume. With ARHL, the speech of others may seem muted, mumbled or slurred. Adults with ARHL generally experience the following symptoms:
Is ARHL the same for men and women? While men develop high frequency hearing loss, women tend to have more problems with lower frequencies (see the Audiogram, bottom, left). Women with ARHL have more difficulty with low-pitched vowel sounds (o, a, ah, i, e), and men have more problems hearing high-pitched consonant sounds (p, h, g, k, f, s, th, ch, sh).
Since the softer high-pitched consonant sounds carry the meaning of speech, people (especially men) with prominent high-frequency hearing loss often have trouble understanding normal speech, especially in background noise.
The figure (bottom) shows average male and female audiograms of a group of men and women (age range 50-89 years, left), and the progression of ARHL from age 20 to age 60 (right panel). Both figures show the prominance of high frequency hearing loss: the left panel shows that men lose the high frequencies more dramatically than women as they age.
In general, ARHL is caused by changes in the inner ear as we age, but genetics, noise exposure, certain medications, smoking, and chronic diseases such as cardiovascular disease, diabetes, and kidney disease, can contribute to the development and progression of ARHL.
ARHL typically occurs when tiny hair cells along the cochlea (a sensory organ inside the inner ear, below) become damaged over time or die. Damaged hair cells (Figure inset, below) short circuit the conversion of sound waves into nerve signals that the brain can interpret as sound. ARHL usually begins with high frequency hearing loss but often progresses to include low frequency hearing problems as well.
Untreated ARHL has been linked to cognitive and emotional disorders, including dementia, self-imposed isolation and depression. Untreated ARHL can damage your physical, emotional, and social health, and strain your relationships with others.
The figure (below) is from a research study by Dr. Li-Korotky … “Age-Related Degeneration of the Organ of Corti in Two Genotypes of Mice.” This study used a mouse model to gain insights into human hair cell degeneration due to aging. The left half of the figure shows banks of healthy hair cells lining the Cochlea. The right half of the figure shows hair cell damage.
This particular research examined hair cell degeneration in mice with different gene structures, leading to different hearing loss results as the mice aged. A scanning electron microscope reveals hair cell damage (hair cells bent over and damaged) due to aging.
Untreated hearing loss can lead to cognitive degeneration and emotional disorders such as dementia, self imposed social isolation and depression, according to a recent study from the National Institute of Aging. The risk for these disorders increases with increasing levels of hearing loss; for every 10 decibels of hearing loss, the probability of developing severe cognitive deficits increases by 20 percent.
Another recent study ( Hearing Loss and Incident Dementia) by Dr. Frank Lin MD, PhD, at the Johns Hopkins School of medicine found a strong link between untreated hearing loss and the development of dementia. A study by Johns Hopkins experts, found that older adults with hearing loss are more likely than their peers with normal hearing to require hospitalization & suffer from periods of inactivity and depression.
The evidence gets a supporting nod from brain scan studies at the University of Colorado (and elswhere), which showed that the brain re-allocates its resources to occupy areas previously occupied by speech processing. Apparently, our brains recognize the diminished capacity associated with hearing loss, and do some internal re-wiring to use those areas for other functions, including sight. Of course, the brain must then borrow resources from cognitive centers to support speech understanding. This creates a “cognitive load” on the brain, and is thought to be a contributor to the development of dementia. These and other studies indicate that hearing deficits can also lead to withdrawal and social isolation, resulting in physical and mental declines.
Mounting evidence of serious consequences resulting from untreated hearing loss underscore why hearing loss should not be considered merely an annoying part of aging, but an important issue for public health.
The consequences of untreated hearing loss are covered in depth, here.
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