Even subclinical hearing loss linked to cognitive decline in seniors

According to a new study, even a subclinical hearing loss is linked to cognitive decline in seniors. The researchers found evidence that even slight declines in hearing, smaller than the usual cutoff for diagnosing hearing loss, are associated with measurable mental decline in the elderly. The study has been published in JAMA Otolaryngology-Head & Neck Surgery.

“People with worse hearing use so much more brainpower to decode the words that are said, they don’t get to process the meaning of what was said, which is the intellectually stimulating part,” said the study’s lead author, Dr. Justin Golub, an assistant professor in the department of otolaryngology-head and neck surgery at NewYork-Presbyterian/Columbia University Irving Medical Center in New York City.

Researchers performed a cross-sectional study to find out the association between hearing and cognition present among individuals who have classically defined normal hearing levels.

The seniors who had hearing problems at the more sensitive threshold would have been considered to have a normal hearing by the current standard for diagnosing hearing loss: 25 decibels, the researchers note. But when the threshold was set at a hearing decline of just 15 decibels, which is comparable to the volume of a whisper or rustling leaves, some of the seniors had trouble hearing.

These people also had “clinically meaningful” cognitive decline, the study team found.

Some scientists suspect that hearing issues might lead to thinking problems because the brain has to redirect so much attention to hearing that it doesn’t get to exercise other mental functions as much.

Golub compares brain fitness to physical fitness. If runners had to think about how to take each step, they wouldn’t get very fast, he explained. Similarly, parts of the brain involved in complex thinking don’t get as much “exercise” when more resources are directed to decoding the words in a conversation.

Beyond that, it’s been shown that “people with worse hearing socialize less - because it’s hard - and thus have fewer intellectually stimulating conversations,” Golub said. “The brain is like a tool that has to be maintained.”

For the new study, Golub and his colleagues analyzed information from the Hispanic Community Health Study (HCHS) and the National Health and Nutrition Study (NHANES), both of which contained data on participants who were given both hearing and cognitive testing.