We Just Learned a Great Deal More About Age-Related Hearing Loss
Also known as presbycusis, age-related hearing loss is one of the most common health conditions encountered in old age. According to the National Institute on Deafness and Other Communication Disorders, roughly a third of people aged 64-74 have hearing loss, and nearly half of people older than 75 experience some form of hearing impairment. Although the precise mechanisms that cause presbycusis have been studied extensively, one question has always eluded scientists.
We know that age-related hearing loss tends to run in families. There's a genetic component to it, meaning that if either or both of your parents started to lose their hearing as they aged, there's a very good chance that you'll lose yours, as well. The one kernel of knowledge that has consistently escaped us is what genes are directly associated with the condition.
This is about more than simply gaining a better understanding of presbycusis. At present, there are very few preventative care options for age-related hearing loss. And there is no treatment known to reverse the effects.
Hearing aids represent one of the most common (and only) available treatments for age-related hearing loss, mitigating the effects of hearing impairment by amplifying sound. Cochlear implants are another option, although the cost and therapy required to use them effectively is a deterrent, especially for older patients. Beyond that, there's nothing.
All any of us can do is try to take better care of our ears. Yet even that doesn't guarantee our hearing will remain intact as we age. It's entirely possible to do everything right in terms of ear care and still end up with hearing loss—and all the conditions that tend to accompany it, including dementia, depression, anxiety, and feelings of social isolation.
To say that it's a grim prognosis would be putting it rather lightly. But a coalition of researchers from King's College London, Karolinska Institute, and Erasmus University may have just unlocked the key to turning things around. Between them, they identified 48 genes linked to hearing loss, including ten completely new variants.
To achieve this, the team performed a meta-analysis of over 700,000 individuals from 17 separate studies. All of these individuals had either self-reported or clinically-diagnosed hearing loss, and all of these individuals consented to genetic testing. It's one of the largest hearing genetics meta-studies ever conducted.
Following up on the preliminary research, the team performed an in-depth investigation of mouse genetics, one which directly confirmed their initial findings—that genes associated with the stria vascularis play a significant role in presbycusis.
As part of the cochlea, the stria vascularis keeps the delicate ion balance in the cochlear fluid surrounding the stereocilia in check. It's long been theorized that as an individual ages, the stria vascularis becomes progressively less capable of regulation. This, in turn, damages the stereocilia, eventually resulting in hearing impairment.
With the release of the study titled “Genome-wide association meta-analysis identifies 48 risk variants and highlights the role of the stria vascularis in hearing loss," this theory is now confirmed. With it, we have a better understanding of the definitive mechanics of presbycusis. And that understanding brings us one step closer to something resembling a cure.
"Our findings identify 10 genes newly linked with hearing loss," co-main author Frances Williams, Professor at King's College London, explained to Neuroscience News. "This study points to genes we could target for screening purposes, drug development and even gene therapy in the future. [It] provides a solid foundation for ultimately improving therapies against hearing loss.”
It's worth noting that this study is far from the only medical research being carried out around hearing loss. There are multiple genetic studies currently in progress, as well as drug trials, gene therapy, and other experimental treatments. The knowledge gained here could further this research, providing a strong basis to improve hearing loss treatments—and perhaps, one day in the future, making hearing loss little more than a distant memory.