Photo credit: Anna Shvets
by Daniel Fink, MD, Chair, The Quiet Coalition
We recently covered a report from Dr. Frank Lin’s research group at Johns Hopkins University describing a relationship between atherosclerosis (hardening of the arteries),as measured by the thickness of cholesterol deposits in the carotid artery (the main artery carrying blood through the neck to the brain) and hearing loss. As I wrote at the time, this is not a new association, dating back to the 1950s.
A new report uses a different method, correlating risk factors for both cardiovascular disease and hearing loss with audiometry findings.
Studies done in the 1960s on isolated populations in Africa to investigate this hypothesis–that hypertension and high cholesterol were the major causes of hearing loss–weren’t successful at elucidating that relationship, because the populations studied ate largely plant-based diets and had almost no noise exposure, so they had neither atherosclerosis nor hearing loss. The handful of studies established the concept that without noise exposure there was no significant hearing loss.
I presented a paper about this at the 12th Congress of the International Commission on Biological Effects of Noise in Zurich in 2017. My analysis was confirmed by a study by Wu et al. from Liberman’s laboratory in Boston, which examined actual ear specimens donated by people with hearing loss after they died. That study showed that the major cause of hearing loss with age was due to noise, not vascular damage.
It’s always good to see a research study from a different laboratory, using different research techniques, that confirms another report. That gives greater credibility to the association first reported.
My concern about these studies, though, is that as in the 1950s and 1960s, a focus on cardiovascular risk factors as the cause of hearing loss ignores the likely real cause of hearing loss with age, noise exposure.
Thousands, maybe tens of thousands of scientific articles in the occupational medicine literature and laboratory research literature show that noise causes hearing loss. That large body of work is so detailed that the exact intracellular, biochemical, and genetic pathways by which noise causes hearing loss are understood to the point where researchers are trying to develop drugs that will block specific pathways to prevent hearing loss after noise exposure.
Reducing cardiovascular risk factors, especially smoking and blood pressure, is a good thing for people with those risk factors. My concern, though, is that focusing on these risk factors rather than on reducing noise exposure avoids dealing with the major cause of noise-induced hearing loss, noise.
So we should all not smoke, watch salt and fat intake, have our doctors check blood pressure and cholesterol, watch our weight, and get sufficient exercise. That will help us live longer and better lives.
But to avoid hearing loss, we must also avoid noise exposure.
If something sounds loud, it’s too loud.
And we should also advocate locally and nationally for quiet, because a quieter world will be a better and healthier world for all.
