Can you hear me, can you hear me running?
Can you hear me running, can you hear me calling you?
“Silent Running (On Dangerous Ground)” by Mike + The Mechanics (Atlantic records, 1985)
Presbycusis warriors unite, for there may yet be hope for saving us from another of the ravages of old age! For those of you who haven’t kept up with your Greek word derivations, I’m referring to the baby boomers in the crowd that have age-related hearing loss. Mike and the Mechanics could have been singing about us in “Silent Running”: we can’t hear you; we can’t hear you running; and unless you talk loudly, we can’t hear you calling us. Which brings us to the topic of this blog: hearing loss; how it impacts fall risk; and what we might do to help. In the AMA Morning Rounds last week, there was an interesting tidbit about a new study published in the current issue of the Journal of the American Geriatrics Society. This new study builds on past research which showed that older adults with hearing loss have more than double the risk of falling, compared to normal-hearing peers. As part of her PhD thesis, author Dr. Laura Lynn Campos looked at the effect of consistently wearing hearing aids and how it impacted the fall risks associated with hearing loss. But before we look at the outcomes from her study, let’s review some background on hearing loss and falls.
Age-related hearing loss is a big deal. Unfortunately, hearing loss may be an inevitable part of getting old—it is estimated that 90 percent of those aged 90 and above are affected by hearing loss. A 2020 Lancet commission report also lists hearing loss as one of the top risk factors for dementia. Johns Hopkins postulates some reasons behind the hearing loss/dementia association: hearing loss strains the brain, making it work harder to hear and to fill in the unheard gaps in conversation. This leaves less cognitive reserve for some of the other higher brain functions like memory and learning. Hearing loss also causes people to be less socially engaged, leading to less intellectual stimulation, leading to less brain activity and less resistance to the development of dementia. The loss of social engagement and intellectual stimulation also increases the risk of depression, another known risk factor of hearing loss. And in a study by Martinez-Amezcua et al, published in JAMA Open Network in 2021, they found that hearing loss was detrimental to several physical functions, with balance, gait speed, and walking endurance being the most negatively impacted functions. Decreased balance then becomes one of the explanations why there is a higher risk of falls in individuals with hearing loss.
Falls in older adults are an even bigger deal than hearing loss. According to the CDC, falls are the leading cause of injury and injury death among adults 65 years and older. In 2020, 14 million older adults reported falling during the previous year, with nearly 39,000 dying as a result of injuries from a fall. Fall-related emergency department visits are estimated at approximately three million visits a year. Direct medical costs for fall-related injuries are estimated to be at $50 billion yearly. Nebraskans fare better than most states when it comes to falls: we rank 18th in the nation for the lowest percentage of older adults with a fall and 13th in the nation for the lowest percentage of deaths from fall injuries.
There isn’t much absolute proof showing the physiologic connection between hearing loss and falls, but there are several plausible theories. One theory is proximity. The cochlear system (responsible for hearing), and the vestibular system (responsible for balance), sit right next to each other in the inner ear. Things that damage one system may also cause damage the other system (like infections, ototoxic drugs, noise exposure, and the ischemic and degenerative effect of aging). The proximity theory is not always obvious: hearing loss is easily recognized with even casual observation; balance problems are not as easily recognized—until after a fall occurs.
Another theory revolves around the Johns Hopkins’ “brain strain” mentioned above: individuals with hearing loss put more effort into the communication process. Hearing loss causes degradation of the complex sounds involved in speech, forcing those individual to utilize more cognitive resources to decode the unheard portion of speech in order to fully comprehend what is being said. This may exhaust some of those cognitive resources, which reduces the availability of those resources for things like balance control, leading to increased risk of falls.
A third theory, which became the focus of Dr. Campos in her research, involves an echolocation process, similar to what is used by bats. We have two ears for a reason, and human brains routinely compare and contrast the sounds received by each ear. The frequency, amplitude, and temporal differences in sounds serve as the means by which the brain performs its echolocation function. Turns out that echolocation is linked to our ability to maintain balance, a fact which becomes obvious in studies where hearing is muffled or blocked. The loss of those auditory “landmarks” produced by our echolocation has consistently shown to make it more difficult for individuals to orient and stabilize themselves in space, thus decreasing their balance. It is also interesting that many of the sounds we use for echolocation and balance start at a frequency range of 2000 Hertz (Hz), which is exactly the frequency range most commonly affected in older adults with hearing loss.
This is the basis of the theory Dr. Campos set out to prove: if balance and hearing are intimately connected, then correcting hearing loss should have a positive impact on balance. Past studies attempting to prove the same theory have shown very inconsistent results. One big difference with those past studies: hearing aid use was a binary selection criteria—they were either worn or they weren’t and daily duration of use was not considered. Dr. Campos used three compare groups in her study: hearing aid users; hearing aid non-users; and consistent hearing aid users (at least three hours daily). Her findings: people who wore hearing aids at least three hours a day had nearly a 50 percent reduction in the odds of experiencing a fall, compared to non-users and those who were infrequent users. The reduction in fall risk was even greater among those who wore hearing aids at least four hours per day.
This study presents us with some interesting possibilities going forward. Should we incorporate a hearing loss question as part of routine fall risk screening and give a ranked score for hearing loss with hearing aid use? And if the use of hearing aids reduces the risk of falling, could hearing aid use also decrease the risk of other hearing-loss-related issues, like depression, and dementia? And lastly, if hearing aids can dramatically decrease the risk of falls (and maybe improve the risks of depression and dementia), shouldn’t the cost of hearing aids be something that traditional Medicare should cover?
