“Hearing loss is strongly linked to a higher rate of cognitive decline and a greater risk of developing dementia over time,” says Frank Lin, associate professor of otolaryngology at the Johns Hopkins University School of Medicine.
“The percentage of people with hearing loss doubles every decade,” says Lin. “By the time you look at adults 70 and older, nearly two-thirds have a clinically significant hearing impairment.”
hearing can affect the brain
“Hearing loss may be an independent hit on the brain,” says Lin, even though it may not affect your blood vessels or your risk of Alzheimer’s. The key theories:
“When you have hearing loss as you age, the cells in your inner ear are damaged and can’t regenerate,” explains Lin.
“So instead of sending a crystal clear signal to the brain, the cells send a much more garbled signal.” Decoding a garbled message takes more effort.
“We know from neuro-imaging studies that the brain has to work harder to process a degraded signal,” says Lin. “So the brain rededicates resources to help with hearing, and it comes at the expense of memory and thinking abilities.”
“Hearing impairment may lead to faster rates of brain atrophy,” says Lin. “That makes sense, because if you have a very impoverished auditory signal, those parts of the brain that handle sound will atrophy faster. And those parts also serve other areas of brain function.”
“For some people, hearing loss leads to a loss of social engagement, which leads to social isolation,” says Lin.
People may feel like a nuisance if they keep asking others to repeat inaudible words, so those with hearing loss often give up and stay on the sidelines. “They’re less likely to be engaged, which is clearly a risk factor for maintaining cognitive health,” says Lin.
Would a hearing aid delay memory loss? “That’s the big question,” says Lin. He is currently planning a five-year trial to find out.
Source: JAMA Intern. Med. 173: 293, 2013.
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