Photo credit: Polina Tankilevitch
by Daniel Fink, MD, Chair, The Quiet Coalition
The Science Direct website reported on an article that covers a possible early detection tool for age-related hearing loss. In a special issue on bioinformatics and computational biology, researchers from Spain report that changes in auditory brainstem responses correlate with presbycusis and could be an early marker for age-related hearing loss.
I lack the research and statistical background to understand this paper fully, but it’s an interesting finding. If the techniques described for Wistar rats could be adopted to humans, they might be clinically useful. Why? In cardiology, there is a body of work showing that the cardiologist telling patients that their coronary calcium score is high helps motivate them to stop smoking, take statin medication and change their diet. The coronary calcium score is a measure of atherosclerosis in the arteries supplying blood to the heart, before the patient has a heart attack.
I caution that rats aren’t humans, and humans aren’t rats, even though we share much of our DNA. Wu et al. noted that animal models may not adequately explain age-related hearing loss in humans. Many animals have been used in hearing research — mice, rats, gerbils, rabbits and monkeys among them — but none live as long as humans, and none shoot guns, operate noisy machinery, or go to rock concerts and use personal listening devices. As Wu et al. stated, “Our data show that hair cell loss in humans is dramatically worse than that in aging animals, suggesting that the high-frequency hearing losses that define human presbycusis reflect avoidable contributions of chronic ear abuse to which animals are not exposed.”
I think it’s important to differentiate in both animal research models and humans between normal physiological aging and premature aging caused by diet, disuse atrophy and exposures. In humans, the prevalence of hearing loss increases with age, but I think much if not most of this is due to cumulative lifetime noise exposure and is not part of normal aging. The skin provides a useful analogy. Ptosis, drooping of the skin, is part of normal aging due to the force of gravity on microcollagen fibers in the dermis. Deep wrinkles and pigmentation changes are not part of normal aging, but are due to sun exposure over time.
Similarly, I think that what is commonly called presybcusis or age-related hearing loss in humans is largely due to excessive cumulative lifetime noise exposure and should be called sociocusis or noise-induced hearing loss in the elderly. Coming back to this new study, if patients know that their auditory brainstem responses show signs of hearing loss, perhaps they could be motivated to reduce noise exposure.
Preventing noise-induced hearing loss is simple and inexpensive. Avoid loud noise exposure, leave the noisy environment or use hearing protection and one’s ears should last a whole lifetime.
