Hearing loss in ‘brain decline link’
The brains of elderly patients with hearing loss seem to decline more rapidly than people with full hearing, a US study shows.
Suggested explanations include rewiring of the brain as hearing declines or social isolation as a result of not having the ability to communicate.
The researchers hope that treating hearing loss can slow the onset of cognitive decline and dementia.
The study was published within the journal JAMA Internal Medicine.
A team of researchers at Johns Hopkins University followed 1,984 people of their 70s for 6 years – all had hearing and mental ability tests first and foremost of the study. There have been then follow-up brain tests over the following six years.
Test scores declined because the study progressed, but patients with a hearing loss deteriorated 40% more quickly.
One of the researchers, Dr Frank Lin, said there have been two main theories about how the 2 will be linked.
Becoming socially withdrawn via hearing loss – reminiscent of unlikely out or being affected by conversation – have been associated with cognitive decline and dementia up to now.
Another idea is “cognitive load”. As hearing declines the brain dedicates more resources to interpreting the info it’s sent, stealing brain power which might be used for other functions.
Cognitive decline may be an early symptom of dementia.
Dr Lin told the BBC: “The most important public health question is that if we treat hearing loss will we delay cognitive decline or dementia?
“That is what all of us care about, however the answer is we just do not know.”
He said individuals with hearing loss used a hearing aid in just 15% of cases within the US “so it’s extremely undertreated”.
Dr Eric Karran, from the charity Alzheimer’s Research UK, said the precise connection between hearing loss and cognitive decline was still unknown.
He said: “Potential social isolation attributable to hearing impairment is a much more likely reason behind this link than there being a shared disease process, although this needs further investigation, this could be an enticing area to review further.
“Most of the people find their hearing becomes worse as they grow older, and age can be the largest risk factor for dementia.
“Understanding whether the 2 are directly linked could give important insight into the condition, but more research might be had to fully answer this query.”