More than one-third of dementia cases can potentially be prevented by controlling nine lifestyle factors. That’s the startling conclusion of a report presented at the Alzheimer’s Association International Conference in London this summer. And the top modifiable risk factor might surprise you.
Some of them, such as smoking, high blood pressure and midlife hearing loss, were not news. What was striking was that midlife hearing loss accounted for 9 percent of the risk of dementia across global populations — the greatest single factor. (The other modifiable risk factors were low education, midlife obesity, late-life depression, diabetes, physical inactivity and social isolation.)
The good news is that treating the hearing loss may help reverse or slow cognitive decline.
“We’re optimistic it will make a difference,” said Dr. Gill Livingston, professor of psychiatry at University College London and lead author of the report, which was published in The Lancet in July. “We’re beginning to do studies to check, here and at Johns Hopkins University.”
Said Jennifer Deal, an epidemiologist and gerontologist at Johns Hopkins on the research team headed by Dr. Frank Lin that’s looking into the connection between hearing loss and accelerated cognitive decline: “What we don’t know yet definitely is whether treating hearing loss will prevent cognitive decline. “We’re excited about asking older adults about this.”
The Lin Research Group at Johns Hopkins has published a pilot study and will start recruitment for a clinical trial in November that will answer that question. Researchers will follow subjects for three years and will have results in about five years, said Deal. (The researchers first announced their findings in 2011.)
Why the Connection Between Dementia and Hearing Loss?
The reasons for the connection between hearing loss and cognitive decline are not clear cut, but researchers have some theories. An important one is that hearing loss tends to lead to social isolation, another risk factor for dementia.
“What keeps your brain healthy is a cognitively rich environment,” said Livingston. “One of the easiest ways to get that is to talk. [But] people who can’t hear often avoid complex social situations.”
When researchers at Johns Hopkins did the pilot study, they saw improvements in social measures among people who had their hearing loss treated with hearing aids, such as the diversity of participants’ social network. Among people in the control group who did not receive hearing interventions, the number of people in their social network decreased in just six months.