Researchers have identified hearing loss as a potential risk factor for dementia and found that greater degrees of hearing loss lead to a higher risk.
Hearing loss is linked to dementia, particularly in adults 60 and older, according to a report published in the February issue of Archives of Neurology.
“In this study, hearing loss was independently associated with incident all-cause dementia after adjustment for sex, age, race, education, diabetes, smoking, and hypertension,” Frank R. Lin, MD, PhD, from the Johns Hopkins School of Medicine in Baltimore, and colleagues reported.
Dr. Lin and colleagues examined 639 adults without dementia between the ages of 36 and 90 to determine the prospective relationship between hearing loss and onset of dementia and Alzheimer’s disease. All participants were enrolled in the Baltimore Longitudinal Study of Aging and underwent audiometry and cognitive testing at various intervals depending on their age.
In total, 125 participants had mild hearing loss (25 to 40 decibels), 53 had moderate hearing loss (41 to 70 decibels), and six had severe hearing loss (more than 70 decibels). Fifty-eight participants were diagnosed with dementia during the average 11.9-year follow-up period, including 37 with Alzheimer’s disease.
“The risk of all-cause dementia increased log linearly with hearing loss severity, and for individuals older than 60 years in our cohort, more than one-third of the risk of incident all-cause dementia was associated with hearing loss,” the researchers wrote.
After adjusting for demographics and other risk factors, Dr. Lin’s group also found that participants who were older, male, and hypertensive had greater hearing loss.
Covariates associated with an increased risk of incident dementia were hearing loss, age, hypertension, hearing aid use, and lower score on cognitive testing.
“Hearing loss may be causally related to dementia, possibly through exhaustion of cognitive reserve, social isolation, environmental deafferentation, or a combination of these pathways,” Dr. Lin commented.
These findings suggest that hearing loss in older adults may be preventable and can be treated with current technology, such as digital hearing aids, cochlear implants, and other rehabilitative strategies that optimize social and environmental conditions for hearing.
Dr. Lin concluded that preventive strategies and mechanisms of dementia require further study: “If confirmed in other independent cohorts, the findings of our study could have substantial implications for individuals and public health…. With the increasing number of people with hearing loss, research into the mechanistic pathways linking hearing loss with dementia and the potential of rehabilitative strategies to moderate this association are critically needed.”
—Ariel Jones