Older adults at greater risk for dementia may be able to protect themselves against cognitive decline by using hearing aids, new research shows.

A study published Monday in the Lancet found that the use of hearing aids can reduce the risk of cognitive decline by about half — 48 percent — for adults with more risk factors for dementia, such as elevated blood pressure, higher rates of diabetes, lower education and income, and those living alone. The study was presented at the Alzheimer’s Association International Conference in Amsterdam.

“It came as a surprise in a good way, seeing that hearing intervention had such a large effect on reducing cognitive decline,” said Frank Lin, professor at Johns Hopkins University School of Medicine and Bloomberg School of Public Health, who was lead author of the study. “It really draws attention to the fact that hearing is really important. And, in many cases, people don’t realize whether or not they have hearing loss, so clearly a first step is getting your hearing checked if you don’t know where your hearing level is.”

Hearing loss is common worldwide, but is often untreated, especially in lower- and middle-income countries. Nearly 2.5 billion people are expected to have some hearing loss, and at least 700 million people will require help with their hearing by 2050, according to the World Health Organization.

Age-related hearing loss nearly doubles the risk for dementia, a 2020 report in Lancet showed, accounting for more than 8 percent of all dementia cases — 800,000 of the nearly 10 million new cases of dementia diagnosed every year. Hearing treatment, though, is now more accessible, as hearing aids are available over-the-counter in the United States.

Hearing aids may cut risk of cognitive …