A friend recently noticed that she couldn’t always hear her phone ringing or family members calling from another room. A hearing test revealed mild loss in high frequencies, which was possibly age-related—she is in her early 60s, and some difficulty with these frequencies often comes with advancing years. She didn’t need hearing aids yet, but she says she’ll monitor the situation and get them if the time comes. She was glad she asked for the test.

Not many people do, nor do most doctors offer. It’s not routine to screen adults for hearing loss even though about 14 percent of Americans older than 12 have trouble hearing. The prevalence increases dramatically with age, to half or more of those over 70. Hearing loss often comes on so gradually that many don’t notice; others ignore it. Only an estimated 15 to 25 percent of adults who would benefit from hearing aids use them, and use is lowest among people who have less access to health care.

Yet recent research has revealed that even mild or moderate hearing loss in older adults is associated with accelerated cognitive decline. People with hearing loss are more likely to develop dementia, and the likelihood increases with the severity of the loss. In 2020 a Lancet Commission on dementia identified hearing loss as the leading modifiable midlife risk factor for later development of the disease.

In July, at the annual meeting of the Alzheimer’s Association, Frank Lin, an otolaryngologist and director of the Cochlear Center for Hearing and Public Health at Johns Hopkins University, presented results from a first-of-its-kind randomized clinical trial of 977 adults between 70 and 84 with untreated hearing loss. One group received best-practice hearing care, including aids, and another group took part in a program about successful aging. Three years later hearing aids did not make much difference to the healthiest participants. But those who were at the higher risk for dementia because of age and underlying health conditions saw a 48 percent reduction in cognitive change if they got hearing aids.

When hearing loss is untreated, the brain’s organization changes, says auditory neuroscientist Anu Sharma of the University of Colorado Boulder. In adults with mild hearing loss, studies show a decrease in gray matter. Sharma found early signs that vision and touch areas of the brain encroach on and repurpose underused hearing areas. Adults with hearing loss also show more activity in working memory areas; they need to make extra efforts just to listen, Sharma says, which may deplete cognitive reserves.

Hearing loss is also associated with more falls, higher health-care costs, and increased loneliness and social isolation. “Hearing is fundamental to healthy aging,” says Nicholas Reed, an audiologist and epidemiologist at Johns Hopkins, who worked with Lin on the cognitive-decline study.

These consequences of hearing loss contributed to the Food and Drug Administration’s decision last year to create a category of over-the-counter hearing aids. Traditional aids, dispensed by audiologists, average $4,700 a pair and are not covered by Medicare or most private insurance. Most of the new OTC devices cost between $500 and $1,900. But quality varies a lot in this range. The high end includes customizable devices. Less expensive aids are preset with limited options—a one-size-fits-all approach that doesn’t really fit all.

Most users of OTC devices still benefit from help getting set up and then troubleshooting devices. But setup help doesn’t have to come from audiologists. In Baltimore, the Johns Hopkins Cochlear Center created a successful program of peer mentoring for older low-income adults with hearing loss.

It’s too soon to assess whether the new devices will close the yawning gap between the large need for hearing aids and the smaller demand for them. In one survey, only about half of nonusers said they would use hearing aids even if they were free. It may help that popular consumer-oriented brands such as Hewlett-Packard and Jabra have jumped into the field. The key to getting around stigma will be “the ubiquity of wanting to hear well” and the sense that “everyone is doing it,” Lin says. If “wireless earbuds also become hearing aids, that changes the whole perspective of what it means to use hearing technology.”