Being hard of hearing, like the need for glasses, is one of the common signs of aging. Seniors may find themselves turning up the television, or find they can't distinguish certain sounds, making it hard to know if someone said “best” or “pest.” This can make it difficult to follow conversations.

Hearing problems can be more than inconvenient. Left untreated, they can lead to impairments in mental abilities, a recent study shows.

“Hearing aids can keep older adults with hearing loss more socially engaged by providing an important bridge to the outside world.”

More than half of adults over age 75 have hearing loss, yet fewer than 15 percent of the hearing-impaired use a hearing aid. Often seniors shy away from them — some for reasons of vanity, others because hearing aids often amplify all sounds equally, so the clatter of forks and knives in a restaurant overpowers the boost it gives their ability to follow conversations around the table.

The new findings may make hearing aids seem a lot more attractive.

The study involved 100 people between the ages of 80 and 99 with hearing loss. Thirty-four of them regularly used a hearing aid. All were given a simple mental test which evaluates cognitive functions by people's vocal responses to verbal commands — the Mini-Mental State Examination (MMSE).

Hearing aid users performed nearly 2 points better than non-users on the MMSE even though they had worse hearing. By comparison, the MMSE scores of people with Alzheimer's disease tend to decline from 2 to 4 points per year.

Those people who did not use a hearing aid and had the greatest hearing loss had lower MMSE scores than those with better hearing — that is, their cognitive function was directly related to their hearing ability.

How can hearing loss lead to mental impairment? The Columbia University researchers point to the way poor hearing tends to isolate people: “We know that hearing aids can keep older adults with hearing loss more socially engaged by providing an important bridge to the outside world,” study co-author, Anil K. Lalwani, said in a statement.

Seniors with hearing problems have been found to have more fall- and accident-related deaths, social isolation and dementia than those without hearing loss. Studies have demonstrated that hearing aid use can improve the social, functional and emotional consequences of hearing loss.

This study adds cognitive impairment to the mix.

“Our study suggests that using a hearing aid may offer a simple, yet important, way to prevent or slow the development of dementia by keeping adults with hearing loss engaged in conversation and communication,” said Lalwani.

Newer hearing aids, which make soft sounds louder while leaving loud sounds unchanged, can make conversations around the dining table more pleasant, but their downside is that they can turn musical compositions inside out, dampening the loud, exciting parts. The best solution may be to remove hearing aids during musical performances.

The study appears in the American Journal of Geriatric Psychiatry.