Scientists Explore Link Between Hearing Loss and Cognitive Decline

In older adults, hearing loss is associated with accelerated cognitive decline, states report published in JAMA Internal Medicine.

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.

Presbycusis (Age-related Hearing Loss)-Causes-Symptoms-Diagnosis-Treatment-FAQs
Presbycusis (age related hearing loss) is the gradual loss of hearing that occurs as people get older. Presbycusis involves progressive sensorineural hearing loss.

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."

Diseases Related to Old Age
Ageing is referred to the accumulation of changes that brings a person closer to death.

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.)

Quiz on Hearing Loss
A little difficulty in hearing is natural with the aging process but if the auditory damage occurs because of other reasons, it can be a cause for concern. Take this quiz to find out how much you know about hearing loss.

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

Anatomy of Ear and Hearing
Ear converts sound waves into electrical impulses that are transmitted to the temporal lobe of the brain through the auditory nerve. It consists of outer, inner and middle sections.

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.(JAMA Intern Med. Published online January 21, 2013. doi:10.1001/jamainternmed.2013.1880.)

Editor's Note: An author made a conflict of interest disclosure for work as a consultant. The work was funded by a grant from the National Institutes of Aging, Research to Prevent Blindness Special Scholar Award and a National Institutes of Health grant. An author also disclosed support. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Source-Eurekalert