Hearing loss may increase the risk of problems with memory and thinking in older adults, a study suggests. The study included 1,984 people in their 70s and 80s. At the start of the study, tests showed they had normal brain function. But 1,162 of them had problems with hearing. Researchers kept track of everyone for about 6 years. They repeated the tests of hearing and brain function 3 times. More than 600 people developed memory or thinking problems. Researchers adjusted their numbers to account for other factors that can increase the risk of mental decline, such as high blood pressure or low education. People with hearing problems were still 24% more likely to develop thinking and memory problems than people with normal hearing. Researchers noted that people who don't hear well may not talk to other people as much. Lack of social contacts is known to increase the risk of mental decline. The journal JAMA Internal Medicine published the study January 22. HealthDay News and USA Today wrote about it.

By Howard LeWine, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

By far, the most common cause of hearing loss is simply getting older. About 33% of all Americans aged 65 through 75 have some hearing loss. That climbs to 50% among people aged 75 and over.

Memory and thinking ability also decline with age. Studies looking at how much hearing loss affects brain function have suggested that the two are linked. But the results have not been all the same. The results of this study show a strong link between hearing loss and a decline in brain function. This study had several strengths compared with earlier ones:

• It included older people who had normal tests for memory and thinking at the start.
• They received standard hearing tests from professionals.
• The same methods were used to test hearing and brain function throughout the study.

During a 6-year period, people with hearing loss had a 30% to 40% faster rate of decline in brain function than those who maintained normal hearing. And the risk of impaired memory and thinking was 24% higher for people with hearing loss. This condition is called cognitive impairment. It includes people with dementia and those more likely to develop dementia.

There are a couple of very plausible reasons why hearing loss could lead to a higher risk of faster decline in brain function. Older people are already prone to social isolation. This is even more likely if they have difficulty hearing. People who don't see or talk to other people much are more likely to develop cognitive impairment and dementia. Reduced hearing, similar to impaired vision, also leads to less brain stimulation.

What Changes Can I Make Now?

There isn't any single cause for age-related hearing loss. Instead, an interlocking set of factors combines to bring it on. They include:

• A family history of age-related hearing loss
• Natural aging processes that affect the ears
• The noisy world many of us live in

Men are more likely to have hearing loss than women.

Uncertainty about the exact cause of age-related hearing loss makes advice on preventing it a challenge. An obvious precaution is to avoid lengthy exposure to loud noises. Otherwise, no one knows for sure what will protect you.

Hearing loss usually occurs slowly. Often the person remains unaware of it or denies it for years. The National Institute on Deafness and Other Communication Disorders suggests answering the following questions to help identify hearing loss:

• Do you have a problem hearing over the telephone?
• Do you have trouble following the conversation when two or more people are talking at the same time?
• Do people complain that you turn the volume of the radio or television up too high?
• Do you have to strain to understand conversation?
• Do you have trouble hearing in a noisy background?
• Do you find yourself asking people to repeat themselves?
• Do many people you talk to seem to mumble or not speak clearly?
• Do you misunderstand what others are saying and respond inappropriately?
• Do you have trouble understanding the speech of women and children?
• Do people get annoyed because you misunderstand what they say?

A "yes" answer to three or more of these questions means that you should talk to your doctor. He or she may refer you for a formal hearing test.

What Can I Expect Looking to the Future?

This study was not able to find out whether using a hearing aid would decrease the risk of cognitive decline. You can expect to see results of those types of studies in the future.