Hearing loss is incredibly common in the elderly, and many consider it a normal part of aging, just like dementia. This is just partly true. Age-related hearing loss is most often connected to damage to the cochlear structures cochlear structures sometimes simply happens with age, but is also often due to other factors, such as noise, diabetes, smoking, vascular diseases, and even social factors, such as education, are thought to be involved.
Indeed, the link between hearing loss and cognitive decline is not a novel idea, and the link has been explored in the past, with the first study linking the two together published in the late 80s. Surprisingly, since then very little research has been conducted on the topic.
But how are the two aspects, hearing loss and cognitive decline, related exactly? It would appear that hearing impairment is associated with a 30-40% rate of accelerated cognitive decline, with more severe hearing loss associated with a higher overall all risk of developing dementia. This may have more than one explanation. First of all, many non-age related factors that promote higher risk of both hearing loss and cognitive decline, are the same for both conditions: diabetes, smoking, and vascular diseases. But impaired hearing may also mean that the brain need to work harder to elaborate sounds, causing it to “overwork”, while bad hearing also decreases social engagement, which is proven to be protective against cognitive decline. Hearing loss may represent the tipping point for a brain that already has developed pathological features such as amyloid-beta plaques and microvascular disease.
Hearing loss in the elderly is notoriously hard to treat, but could the use of hearing aid devices reduce the risk of dementia in those with hearing complaints? It is not sure: researchers have explored this possibility but they noted how individuals willing to try out hearing aid devices and technologies are in general healthier and of higher socioeconomic status, thus creating a positive bias of seeing a protective effect, but they are at the same time also more likely to have more severe hearing problems, thus leading to a negative bias. More research is needed, and hopefully will shed light on the link between hearing loss and cognitive decline.
Lin, F. R, Marilyn, A. (2014), Hearing Loss and Dementia – Who’s Listening?, Aging Mental Health, 18(6), 671-673.