November 28, 2014
Senior man with Hearing Loss

Does Hearing Loss Harm Thinking?

by Berkeley Wellness  |  

It’s estimated that 48 million Americans have some degree of hearing loss, which increases with age. Most go untreated, largely due to the high cost of hearing aids (usually not covered by insurance) or because they fear looking “old.” And some people just consider hearing loss a normal, and relatively harmless, part of aging. But there’s growing evidence that hearing loss has adverse effects beyond the obvious ones—notably, that it may increase the risk of cognitive problems.

Most recently, a study in JAMA Internal Medicine assessed the cognitive and hearing levels of 1,984 older adults (average age 77). Compared to those with normal hearing, those with hearing loss had lower scores at baseline on a global cognitive test and were more likely to have significant cognitive impairment after six years. This held true after the researchers controlled for age, smoking, stroke history, hypertension, depression and other factors that can affect cognition. Moreover, they had a 30 to 40 percent faster rate of cognitive decline, and the worse the hearing, the worse the deterioration. Two previous studies in 2011 by the same lead author—a hearing loss expert at Johns Hopkins University—had similar findings.

What’s the connection between hearing loss and impaired cognition? The article notes a few possibilities. One is something called cognitive load, in which hearing loss compromises cognitive processes, such as working memory, because so much more effort is needed to process auditory information. Hearing loss also often increases social isolation and loneliness, which are risk factors for cognitive decline and dementia, presumably due to reduced stimulation. Even if someone with hearing loss maintains social connections, not being able to hear well can lead to feelings of isolation. Another possibility is that hearing loss and cognitive decline share the same underlying physiological mechanisms, such that when one function is impaired, so is the other.

Would a hearing aid help? It’s reasonable to think so, but the study could not adequately address this question. A study published two decades ago in the Annals of Internal Medicine showed cognitive benefits, but more research is clearly needed. In the meantime, there is good reason to treat hearing loss, which affects quality of life in so many ways, including increasing the risk of falls, social isolation and depression. If doing so even slightly heads off dementia, that would be another plus.