Many people suffer from hearing loss…
In fact, the latest available statistics show that over 10% of the U.S. population reports difficulty hearing! That’s more than 31 million people! And as the Baby Boomer generation continues to age, that number promises to increase dramatically!
Are you one of those millions of people who does not hear as well as they once did? If so, you are certainly not alone. Consider these statistics reported by Sergei Kochkin, Ph.D., Executive Director of the Better Hearing Institute :
- 3 in 10 people over age 60 have hearing loss;
- 1 in 6 baby boomers (ages 41-59), or 14.6%, have a hearing problem;
- 1 in 14 Generation Xers (ages 29-40), or 7.4%, already have hearing loss;
- At least 1.4 million children (18 or younger) have hearing problems;
- It is estimated that 3 in 1,000 infants are born with serious to profound hearing loss.
In addition, studies have linked untreated hearing loss to emotional, physical, mental, psychological and even economic disadvantages! And, to make matters even worse, there are many “myths” about hearing loss that prevent those with hearing loss from doing anything about it.
Causes of Hearing Loss
One of the most common “myths” about hearing loss is that only “old people” suffer from it! In fact, the reverse is true! The majority (65%) of people with hearing loss are younger than 65 and six million people in the U.S. between 18 and 44 suffer from hearing loss (Better Hearing Institute website).
The truth is that there are several causes of hearing loss with “exposure to noise” ranking high among the reasons. The primary causes of hearing loss are:
- Exposure to noise
- Family history of hearing loss
- Aging process
- Head trauma
Types of Hearing Loss
Not all hearing loss can be corrected through the use of hearing aids or alternative listening devices. The type of hearing loss determines the specific treatment required.
There are four types of hearing loss:
- Conductive: This could be caused by something as simple as earwax buildup!
- Sensorineural: This is caused when tiny hairs in the cochlea are missing or damaged.
- Mixed: This is a combination of conductive and sensorineural hearing loss.
- Central: Strokes and central nerve diseases are often the cause of this type of hearing loss.
Hearing Loss Linked to Accelerated Brain Tissue Loss
Although the brain becomes smaller with age, the shrinkage seems to be fast-tracked in older adults with hearing loss, according to the results of a study by researchers from Johns Hopkins and the National Institute on Aging. The findings add to a growing list of health consequences associated with hearing loss, including increased risk of dementia, falls, hospitalizations, and diminished physical and mental health overall.
For the study, Frank Lin, M.D., Ph.D., and his colleagues used information from the ongoing Baltimore Longitudinal Study of Aging to compare brain changes over time between adults with normal hearing and adults with impaired hearing. The Baltimore Longitudinal Study of Aging was started in 1958 by the National Institute on Aging to track various health factors in thousands of men and women.
Previous research from other studies had linked hearing loss with marked differences in brain structure compared to those with normal hearing, both in humans and animals. In particular, structures that process information from sound tended to be smaller in size in people and animals with impaired hearing. Lin, an assistant professor at the Johns Hopkins University schools of medicine and public health, says it was unknown, however, whether these brain structural differences occurred before or after hearing loss.
As part of the Baltimore Longitudinal Study of Aging, 126 participants underwent yearly magnetic resonance imaging (MRI) to track brain changes for up to 10 years. Each also had complete physicals at the time of the first MRI in 1994, including hearing tests. At the starting point, 75 had normal hearing, and 51 had impaired hearing, with at least a 25-decibel loss.
After analyzing their MRIs over the following years, Lin and his colleagues, reporting in an upcoming issue of Neuro image, say those participants whose hearing was already impaired at the start of the sub-study had accelerated rates of brain atrophy compared to those with normal hearing. Overall, the scientists report, those with impaired hearing lost more than an additional cubic centimeter of brain tissue each year compared with those with normal hearing. Those with impaired hearing also had significantly more shrinkage in particular regions, including the superior, middle and inferior temporal gyri, brain structures responsible for processing sound and speech.
That structures responsible for sound and speech are affected in those with hearing loss wasn’t a surprise, says Lin — shrinkage in those areas might simply be a consequence of an “impoverished” auditory cortex, which could become atrophied from lack of stimulation. However, he adds, these structures don’t work in isolation, and their responsibilities don’t end at sorting out sounds and language. The middle and inferior temporal gyri, for example, also play roles in memory and sensory integration and have been shown to be involved in the early stages of mild cognitive impairment and Alzheimer’s disease. “Our results suggest that hearing loss could be another ‘hit’ on the brain in many ways,” Lin explains.
The study also gives some urgency to treating hearing loss rather than ignoring it. “If you want to address hearing loss well,” Lin says, “you want to do it sooner rather than later. If hearing loss is potentially contributing to these differences we’re seeing on MRI, you want to treat it before these brain structural changes take place.”
Lin and his colleagues say they plan to eventually examine whether treating hearing loss early can reduce the risk of associated health problems.
The research was supported by the intramural research program of the National Institute on Aging, the National Institutes of Health’s National Institute on Deafness and other Communication Disorders (K23DC011279), a Triological Society/American College of Surgeons Clinical Scientist Development Award and the Eleanor Schwartz Charitable Foundation.
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