“We were pleasantly surprised to see that the hearing intervention was so effective in reducing cognitive decline,” he said. Frank Lynn, Professor at the Johns Hopkins University School of Medicine and the Bloomberg School of Public Health, and the lead author of the study. “It really draws attention to the fact that hearing is so important. And often people are unaware if they have hearing loss, so obviously getting a hearing test is the first step if you don’t know your hearing level.”
Hearing loss is common around the world, but often goes untreated, especially in low- and middle-income countries. Nearly 2.5 billion people are expected to suffer from some form of hearing loss, according to the report, and by 2050 at least 700 million people will need hearing aids. world health organization.
Age-related hearing loss almost doubles the risk of dementia. 2020 report published in The Lancet It accounts for more than 8% of all dementia cases and 800,000 of the approximately 10 million new diagnoses of dementia each year. However, hearing aids are now available over-the-counter in the United States, making hearing care more accessible.
Over 3 years, randomized control trial They studied nearly 1,000 older adults between the ages of 70 and 84 at four facilities in the United States. Participants included older adults with community atherosclerosis risk (ARIC), an ongoing study of cardiovascular health, and healthier-than-adults with ARIC. Both groups were from the same community at each site.
Combining the two groups showed that hearing aid use had no significant effect on delayed cognitive changes. However, in a separate analysis of the ARIC group, a group at high risk of dementia, the researchers found that hearing interventions (counseling with an audiologist and using hearing aids) were important. It was very effective in reducing cognitive decline. Those considered at high risk for dementia were older and had lower cognitive scores, among other factors.
The researchers suggested that healthier participants experienced slower rates of cognitive decline when these groups were combined, which may have limited the effectiveness of hearing aids.
It is still unclear whether hearing treatment reduces the risk of developing dementia in the long term. “That’s the next big question that we don’t yet have an answer for,” said Lin, who is also director of the Cochlear Center for Hearing and Public Health at Johns Hopkins University. They said they are planning a long-term follow-up study to answer that question.
Over the past decade, he said, many studies have been conducted to try to understand why people with hearing loss tend to have less cognitive function. Justin S. Golub, associate professor of otorhinolaryngology at Columbia University Irving Medical Center. One theory is that people with hearing loss need a lot of effort to understand what others are saying, and the brain power required leaves them with fewer cognitive resources to process the meaning of what they hear.
Another theory has to do with the structure of the brain. Studies have shown that the temporal lobe of people with hearing loss tends to shrink faster because it receives less auditory input from the inner ear. The temporal lobe is connected to other parts of the brain, “which can have cascading effects on brain structure and function,” said Golub, who was not involved in the Lancet study.
A third theory is that people with hearing loss tend to be less social and, as a result, less cognitively stimulated.
While there have been small clinical trials to show that hearing aid wearers tend to improve cognitive function, no large-scale studies have looked at the long-term cognitive benefits of wearing hearing aids, Golub said.
“This is really unique, really groundbreaking,” he said.
