An American study has found that even a very mild hearing loss of not more than 15 dB results in measurable mental decline in seniors.

The researchers found that there was an association between decreasing hearing and decreasing cognition among people classically considered to have normal hearing. This association remained present despite controlling for confounders, including age, sex, educational level, cardiovascular disease or hearing aid use.

The study included 6,451 participants from two studies. Participants aged 50 years or older from the general Hispanic population in the Hispanic Community Health Study (HCHS) and participants from the general US population in the National Health and Nutrition Examination Study (NHANES).

Hearing aids were only used by a very small number of participants.

Also mild hearing loss

In the study, decreased hearing was independently associated with decreased cognition in adults with normal hearing (pure-tone average 25 dB) across all cognitive tests in the HCHS study. When using a stricter hearing loss cut point (15 dB), the researchers also found an association was also present in the NHANES study.

Use resources to hear

“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 New York Presbyterian/Columbia University Irving Medical Center in the US to Reuters.

Brain fitness

To Reuters, Golub compared 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, Golub explained.

“People who had difficultly hearing a whisper (but technically still had normal hearing), scored 6 points worse on a test of speed and attention than people who had absolutely perfect hearing,” Golub told Reuters “This took into account other factors, such as age. Scientists say that the 6-point change could make a meaningful difference in day to day function.”

Previous studies

Several previous studies have also found a relationship between hearing loss and cognitive decline.

The study, “Association of Subclinical Hearing Loss With Cognitive performance”, was published in the journal JAMA Otolaryngology Head & Neck Surgery.

Sources: www.reuters.com and the journal JAMA Otolaryngology Head & Neck Surgery.