Photo credit: NIC LAW
by Daniel Fink, MD, Chair, The Quiet Coalition
JAMA Network Open, the JAMA Network’s open access online journal, carried a report from France about hearing loss, hearing aids and cognition. The research was based on the CONSTANCES study, with over 60,000 participants between the ages of 45 and 69. The study did not include participants who were missing data about hearing or cognition.
Hearing was measured by standard audiometry from 500-8,000 hertz, and researchers used five tests administered by trained neuropsychologists to test cognitive function. Researchers asked participants if they used hearing aids, but they did not ask about daily use or how many hours a day the participants wore their hearing aids.
The is an observational study only, with statistical correlations reported. The results showed an association between hearing loss and worse cognitive function, but did not find any benefit of hearing aids on cognitive function. Observational studies do not establish causation, and instead suggest avenues for additional research.
My criticism of the study is the use of limited frequency pure tone audiometry. This is appropriate for screening purposes, but misses auditory damage that more sensitive tests might discover. These more sensitive tests include extended-range audiometry up to 12,000 or even 20,000 hertz; speech-in-noise testing; distortion product otoacoustic emissions testing; and questions about the presence of tinnitus and hyperacusis, as used by Liberman et al. in a 2016 paper about hidden hearing loss. That research found evidence of auditory damage that was not present on screening audiometry by using the more sensitive tests.
A possible reason for the French study not showing any benefit from hearing aid use is that the study population was much younger than the populations of studies showing correlations between hearing loss and dementia. Dementia is less prevalent in younger people, and relatively rare under age 70. For example, in the paper by Lin et al. reporting an association between hearing loss and dementia, the subjects with moderate to severe hearing loss were 77 years old.
I’m not sure what, if anything, this study adds to our knowledge. There’s no dramatic conclusion, and as noted above there may be some methodology issues with the research. Despite these concerns, all research, even when inconclusive, adds to our collective knowledge.
But no more research is needed to know that noise exposure causes hearing loss in workers and the general public. If something sounds loud, it’s too loud and the listener’s auditory health is at risk. Turn down the volume, leave the noisy event or use hearing protection and one’s ears should last a lifetime.
