Hearing loss appears to be associated with accelerated cognitive decline and cognitive impairment in a study of older adults, according to a report published Online First by JAMA Internal Medicine, a JAMA Network publication.
The prevalence of dementia is projected to double every 20 years because of the world's aging population so identifying the factors and understanding the pathways that lead to cognitive decline and dementia in older adults is a public health priority, the authors write in the study background.
Frank R. Lin, M.D., Ph.D., of The Johns Hopkins Center on Aging and Health, Baltimore, studied 1,984 older adults (average age about 77 years) enrolled in a prospective observational study that began in 1997-1998.
A total of 1,162 individuals with baseline hearing loss had annual rates of decline in test scores that measured global and executive function that were 41 percent and 32 percent greater, respectively, than those among individuals with normal hearing. Compared to those individuals with normal hearing, individuals with hearing loss at baseline had a 24 percent increased risk for incident cognitive impairment, according to the study results.
"Our results demonstrate that hearing loss is independently associated with accelerated cognitive decline and incident cognitive impairment in community-dwelling older adults," the authors comment. "The magnitude of these associations is clinically significant, with individuals having hearing loss demonstrating a 30 percent to 40 percent accelerated rate of cognitive decline and a 24 percent increased risk for incident cognitive impairment during a six-year period compared with individuals having normal hearing."
The authors suggest that, on average, individuals with hearing loss would require 7.7 years to decline by five points on the 3MS (the Modified Mini-Mental State Examination, a commonly accepted level of change indicative of cognitive impairment) compared with 10.9 years in individuals with normal hearing.
"In conclusion, our results suggest that hearing loss is associated with accelerated cognitive decline and incident cognitive impairment in older adults. Further research is needed to investigate what the mechanistic basis of this observed association is and whether such pathways would be amendable to hearing rehabilitative interventions," the study concludes.
(JAMA Intern Med. Published online January 21, 2013. doi:10.1001/jamainternmed.2013.1868.)
Editor's Note: An author made conflict of interest disclosures about being a consultant and an unpaid speaker. Study funding includes contracts from the National Institute on Aging, The Johns Hopkins Older Americans Independence Center and by grants from the National Institute of Nursing Research, the National Institute on Deafness and Other Communication Disorders and a Triological Society/American College of Surgeons Clinician Scientist Award. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
Research Letter: Prevalence of Hearing, Vision Impairment in the United States
CHICAGO - In a related research letter that analyzed data from the 1999-2006 cycles of the National Health and Nutritional Examination Surveys (NHANES), researchers estimated that approximately 1.5 million Americans 20 years or older had dual sensory impairment (DSI) in hearing and vision loss, with nearly all the affected individuals being older adults. For individuals younger than 70 years old, the prevalence of DSI was less than 1 percent but among individuals 80 years or older, 11.3 percent had DSI and 19 percent were free of any sensory impairment.