Treating hearing loss may stave off dementia

A study has found a link between the very early stages of hearing loss and cognitive decline. 

Researchers at Columbia University have found that brains start to declinefrom the very first stages of hearing loss, leading to an impairment of memory and cognitive skills.

Past studies had found that people with age-related hearing loss are more likely to have impaired cognition, which has led to the belief that hearing loss may trigger cognitive decline. However, these studies had only looked at patients diagnosed with hearing loss,  which is defined as the inability to hear sounds under 25 decibels (dB).

For the new study, researchers tested the hearing and cognitive levels of 6,451 adults (average age 59) and found that for every 10 dB decrease in hearing, there was a significant decrease in cognitive ability, a pattern seen across the entire spectrum of hearing. With the largest decrease in cognitive ability occurring in those whose hearing was just starting to become impaired, just 10 dB off the ‘perfect hearing mark’.

Dr Justin S. Golub, assistant professor of otolaryngology-head & neck surgery at Columbia University Vagelos College of Physicians and Surgeons and a hearing specialist at Columbia University Irving Medical Center and NewYork-Presbyterian said:

‘Physicians in this field have used 25 dB—about the loudness of a whisper—to define the border between normal hearing and mild hearing loss in adults, but this level is arbitrary.

‘It has been assumed that cognitive impairment wouldn’t begin until people passed this threshold. But no one actually looked at whether this was true.’

Dr Golub said the current study did not address whether hearing loss causes cognitive impairment, adding that it’s possible that early declines in both hearing and cognitive performance are related to common aging-related processes.

‘Most people with hearing loss believe they can go about their lives just fine without treatment, and maybe some can.

‘But hearing loss is not benign. It has been linked to social isolation, depression, cognitive decline, and dementia. Hearing loss should be treated. This study suggests the earlier, the better.

‘But it’s also possible that people who don’t hear well tend to socialize less and, as a result, they have fewer stimulating conversations. Over many years, this could have a negative impact on cognition.

‘If that’s the case, preventing or treating hearing loss could reduce dementia incidence by more than 9%, according to a recent analysis published in The Lancet.’

This comes as UK charities Action on Hearing Loss and Alzheimer’s Research UK have teamed up to invest more than £150,000 into a research project looking into the links between the two conditions.

A spokesman for the charities said researchers will look to establish if dementia is directly caused by hearing loss, if dementia is an indirect consequence of social isolation caused by hearing problems, or if hearing loss is a marker of biological factors that increase the risk of both hearing loss and dementia. They will also investigate whether hearing aids can help reduce the risk of dementia.

Dr Ralph Holme of Action on Hearing Loss said:

‘Hearing loss and dementia can have devastating consequences, and with an ageing population it is an issue we can no longer ignore.

‘We will also be funding research looking at whether inflammation is the link between hearing loss and dementia. We hope the research we are funding will ultimately lead to new treatments.’

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