Hearing aids can stabilise cognitive function in older people with hearing loss, according to a new Melbourne study that suggests hearing intervention may delay cognitive decline and dementia.
Writing for Pursuit, the University of Melbourne researchers said it was previously known that hearing loss was associated with accelerated cognitive decline, raising the risk of dementia for older people with untreated hearing loss.
Their study expanded on this by finding hearing aids can extend brain function by years.
They found older people with hearing loss demonstrated significantly better cognitive performance for at least three years after a hearing aid was fitted than peers without hearing aids.
The study, published in the Frontiers in Neuroscience journal, compared cognitive performance in two groups aged 60 years or older. One group all had hearing loss and used hearing aids while the other group from an ageing study did not use hearing aids.
Lead author was audiologist Professor Julia Sarant who leads the Hearing Loss and Cognition Program in the University of Melbourne’s Department of Audiology and Speech Pathology.
“We assessed cognitive performance using computerised card games, starting before hearing aids were fitted and then at 18-month intervals, using only visual instructions,” Sarant said.
After three years, the hearing aid group showed overall cognitive stability but the non-hearing aid group had declined significantly on three of four cognitive tests.
“Our research shows that hearing aid use may be an important large-scale public health strategy for delaying cognitive decline, helping to reduce or slow the global burden of dementia,” she said.
The researchers said hearing loss often occurred many years before dementia onset, creating a window of opportunity to address hearing loss early and hopefully slow development of hearing-loss-associated dementia.
The preventative step of wearing a hearing aid was best taken before hearing loss started to impact brain function while the brain was still flexible, they added. This allowed brain re-wiring that occurs when hearing is restored.
Sarant said the rate of cognitive decline was thought to increase with increasing severity of hearing loss. Those with mild hearing loss had almost double the risk of dementia than someone with normal hearing, and people with severe hearing loss had almost five times the risk.
Additionally, about 40% of dementia cases were thought preventable and of 12 potentially modifiable risk factors, hearing loss was the largest.
She explained that theories of why hearing aids could help promote cognitive health included that decreased auditory stimulation to the brain and reduced processing of sound could change brain structure and function. Reduced environmental stimulation and social participation due to hearing loss may also contribute to psychological issues such as loneliness and depression, which changes brain structure and function.
The researchers said more studies were needed to confirm their findings using appropriate measures of cognition, hearing and device use, with longer follow-up.
Collaborators included the university’s Department of Economics, Cogstate, the Florey Institute of Neuroscience and Mental Health, Melbourne Hearing Care Clinic, Sonova AG and the Victorian Department of Health.
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