During the past decade, several major studies determined that hearing loss, which the Hearing Loss Association of America said impacts more than 48 million Americans, may increase the risk of developing cognitive problems, including Alzheimer's disease and dementia. Those with mild hearing impairment are nearly twice as likely to develop dementia as those with normal hearing, with the risk increasing to three times as likely for those with moderate hearing loss and five times as likely for those with severe hearing impairment.
Results from a University of North Texas study found a positive connection between the use of hearing aids and improvements in cognition in older adults who had already been diagnosed with moderate dementia, but the researchers note that auditory training results in more improvement than wearing hearing aids without the training.
Amyn Amlani, associate professor in UNT's Department of Audiology and Speech-Language Pathology, and Kyle Harber, a doctoral audiology student, provided hearing aids to 12 older adults who had been diagnosed with dementia 18 months to three years before the study began.
Harber, who recently presented the research at the American Academy of Audiology annual conference, and Amlani wanted to determine the extent that hearing aids could provide brain plasticity -- the ability of the brain to modify its own structure and function following changes within the body or in the external environment. In addition to receiving hearing aids, selected participants in the group received online auditory training at home for four weeks, using the software five days a week.
All of the study participants completed tests on their auditory, verbal and visual recall as well as their working memory -- the ability to remember and use relevant information at a later time after being provided the information. The study participants were initially being tested before being fitted for hearing aids and were tested again four, 12, and 24 weeks later. The spouse or another close relative of each participant was asked about improvements in the person's cognitive abilities.
Harber said that after several of the dementia patients wore the hearing aids for 12 weeks, their abilities to read, talk on the phone, and carry on a conversation in person improved. Many of the patients who previously could not be left alone increased their independence along with their cognitive abilities, and they could stay alone in their homes for short periods of time, he said.
Amlani added that one study participant helped to plan his own 50th wedding anniversary party, and another, a former journalist, started being able to discuss current events with his wife.
"We expected to see an initial upward trend in cognition because the brain was rewiring itself with the use of hearing aids. But the brain eventually reaches its ceiling in plasticity," he said.
Harber said that although better amplification leads to a positive trend, "no significant improvement in cognition was seen until auditory training was brought into the mix."
"Just 30 days of training made a difference," he said.
The researchers say more research is needed on the extent of long-range auditory training on plasticity.
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