By EJ Mundell
THURSDAY, Dec. 7, 2017 (HealthDay News) -- Age can often bring a loss of hearing, and for some, mental decline in the form of dementia. But are the two linked?
New research does suggest that hearing loss raises the odds for dementia, but the jury is still out on whether one condition actually causes the other, experts say.
According to a team of Irish researchers at Trinity College Dublin, approximately one-third of adults older than 65 years experiences age-related hearing loss. And prior research suggests that a loss of hearing often -- but not always -- precedes the onset of dementia by about 5 to 10 years.
In the new study, a team led by Trinity's David Loughrey reviewed data from 36 studies that included more than 20,000 people across the world. The investigators found a small association between age-related hearing loss and increased risk for mental decline, mental impairment and dementia.
"The associations, although small, were comparable in size and significance with other more commonly researched risk factors" for dementia, the study authors wrote. For example, looking only at the best-conducted, prospective studies, age-related hearing loss was tied to a 22 percent higher odds for cognitive (mental) impairment and a 28 percent higher risk for any kind of dementia.
However, looking at Alzheimer's disease in particular, Loughrey's group saw no association between hearing loss and that brain-robbing disorder.
The researchers stressed that they couldn't prove any cause-and-effect relationship. But if hearing loss is tied to dementia, that's doesn't mean aging adults are helpless to prevent either condition, one geriatrician said.
"It does appear that hearing loss is a modifiable risk factor for cognitive decline as we get older -- this is good news for older adults because hearing loss can be diagnosed easily and treated successfully when using proper hearing aids," noted Dr. Gisele Wolf-Klein. She directs geriatric education at Northwell Health in Great Neck, N.Y.
Dr. Ian Storper directs otology at the Center for Hearing and Balance Disorders at the New York Head and Neck Institute, part of Lenox Hill Hospital in New York City. Reviewing the findings, he stressed that the study couldn't prove that diminished hearing helps cause dementia, so older Americans who are having hearing difficulties shouldn't panic.
Also, the study "does not suggest that hearing loss is the only risk factor" for dementia, Storper said. And he agreed with Wolf-Klein that if hearing loss is a risk factor for cognitive decline, "it could be a preventable risk factor by using hearing aids, if possible, which will also help you hear better."
The findings were published Dec. 7 in the journal JAMA Otolaryngology-Head & Neck Surgery.