New Study Links Dementia to Mild Hearing Loss – JAMA Internal Medicine

Millions of aging, hearing-impaired adults are more likely to suffer early memory and thinking problems than adults without hearing loss, a study from JAMA Internal Medicine finds.

This study shows that older adults with mild hearing loss (25 db) developed cognitive problems 30% to 40% faster. “That’s when you begin noticing trouble hearing and understanding in settings like a busy restaurant,’’ says doctor of Audiology, Robert Smith.
Most estimates show 30% of people, 70 or older, in the USA alone have some degree of hearing loss. About 7 million people in the USA have some form of dementia, and numbers are expected to double every 20 years.

“This shows me how important it is for physicians to discuss hearing with their patients and be more involved in addressing hearing problems,” says Dr. Smith.

The study, funded by the National Institute of Health, didn’t examine why cognitive skills decline when mild hearing loss occurs. Future research preformed with hearing devices may show that the problem is prevented.

During this study the researchers followed 1,984 adults ages 75-84 from 2001 to 2007, accounting for factors known to contribute to loss of brain function — high blood pressure, diabetes and stroke. All participants had normal brain function and hearing when the study began.

They were given two brain tests; one at the start of the study asked them to memorize words, follow commands and answer questions about year, date and time. The other test timed them on how long it took to match numbers to symbols. Both cognitive tests and hearing tests were repeated three more times to gauge decline.

Decline (in memory) was statistically significant in the hearing-impaired, compared with people with normal hearing, the study shows. Those who suffered hearing loss took 7.7 years to show mental decline, vs. 10.9 years for those with healthy hearing.

Social isolation, a risk factor for dementia, is one possible explanation for cognitive decline. Underlying brain damage that leads to both hearing and cognitive decline may be another reason.

Doctor Smith determines that constantly having to expend more (mental) energy trying to understand what is being heard, called auditory deprivation, pays a heavy cost on the mind. Meaning, hearing loss may not directly contribute to dementia, but leads to cognitive load on the brain.

This link between mild loss of hearing and cognitive skills is a siren call for public awareness. Not just with the aging public but also with hearing loss among younger adults, who are unaware of it when it is relatively mild.

Dr. Smith goes on to say, “As hearing ability declines with age, interventions such as hearing aids should be considered not only to improve hearing, but to preserve the brain. Giving the brain time to relearn specific sounds with amplification is critical, this may take up to 3 months.”

People hear differently, and those with even mild hearing loss may have to work harder to understand complex
sentences.

Multiple sources questioned on hearing loss and dementia all agree on a key point, even mild hearing loss is easily diagnosed using the latest
testing equipment.

Everyone, 50 or older, should have a hearing test every year, similar to a regular visit to a dentist. Early detection, and the proper diagnosis could prevent cognitive problems in the future.

Excerpts from the Study:published January 21, 2013 at JAMA Internal online.