Mounting evidence has established a strong link between untreated hearing loss and diminished cognitive function, including dementia and Alzheimer’s disease. Studies also link untreated hearing loss to other medical and emotional problems, including depression.
Though it can’t be said that hearing loss causes dementia, an important link has been established, reinforced by related statistical and brain scan studies, and backed by compelling theories for how hearing loss may cause mental decline.
A 2011 study by Johns Hopkins and the National Institute on Aging found that older adults with hearing loss were significantly more likely to develop dementia than elderly adults with normal hearing, even after accounting for other conditions known to cause dementia, such as hypertension.
A 2013 Johns Hopkins study showed that older adults with hearing loss were more likely to develop thinking and memory problems than seniors with normal hearing, and the rate of mental decline was 30-40 percent faster for the older adults with hearing loss.
A 2014 study by Johns Hopkins found strong evidence that hearing loss is linked to accelerated brain tissue loss in elderly adults. Most of us lose some brain tissue when we age, but the study found that older adults with hearing loss experienced much more brain tissue loss than others with normal hearing. Remarkably, a large share of the brain shrinkage occurred in areas of the brain responsible for speech and sound processing.
A 2015 study by the University of Colorado’s Department of Speech Language and Hearing Science, found that the brain responds to brain tissue loss(from hearing loss) by rearranging its neuronal priorities. As a consequence of these shifting priorities, areas of the brain once responsible for higher-level decision-making are reassigned to speech and sound processing. Unfortunately, this adaptive rewiring of brain function also decreases the resources available for thinking functions, and that may explain why hearing loss is linked to dementia, as reported in other studies.
On a positive note, new research just published in the Journal of the American Geriatrics Society by researchers at the French National Institute for Health and Medical Research in Bordeaux France, found that hearing aids can slow the cognitive decline associated with hearing loss.
The Bottom Line? The evidence serves as a cautionary tale: hearing loss can end badly if unattended, but treatment with hearing aids may forestall a bad ending to a great story.
Dr. Li-Korotky, AuD, PhD, MD, CCC-A, F-AAA, is Board Certified in Audiology, and CEO of Pacific Northwest Audiology. 541-678-5698, www.pnwaudiology.com
