New research has found that hearing loss in the elderly may speed up the onset of dementia and cognitive impairment.
The study, done by the Johns Hopkins Center on Aging and Health, was recently published online by the journal JAMA Internal Medicine, according to a press release from Johns Hopkins.
http://www.eurekalert.org/pub_releases/2013-01/jaaj-hlm011713.php
Dr. Frank Lin studied 1,984 older adults, whose average age was about 77 years, enrolled in an 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,” the press release said.
Compared to those with normal hearing, the elderly with hearing loss had a 24 percent increased risk for 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 study’s authors said in a statement.
“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 said.
They suggested that, on average, the elderly 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,” the study concludes. “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.”
Lin had several explanations for the link between hearing loss and dementia, according to The Huffington Post.
No. 1, Lin said that hearing loss means that the inner ear isn’t doing a good job of converting sound into a signal to the brain. That means that the brain is getting a garbled message, according to The Huffington Post, and therefore starts to deploy more effort into processing sounds.
That means some other brain function has to suffer, and MRIs have shown that the part of the brain dealing with memory is what suffers, The Huffington Post reported.
Secondly, Lin said that those with a hearing loss can become withdrawn and do less socializing, and isolation is one of the risk factors for dementia.
The prevalence of dementia is projected to double every 20 years because of the world’s aging population, according to the study’s authors, so figuring out the factors that lead to cognitive decline is a public health priority.
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