Hearing loss has emerged as an important risk factor for dementia.

Compared to people with normal hearing, many studies have found those with a declining ability to hear have an increased risk of cognitive decline or dementia. Depending on the study, the increase in risk varied from almost double to five-fold.

Yet a recent report from the World Health Organization didn’t advise people to get their hearing checked. In their view, the studies supporting a link to Alzheimer’s were too small and therefore inconclusive.

By the time the researchers produce their next updated report they may have changed their minds.

Here’s why. . .

Improves Memory and Concentration

A recent report published in the Lancet found hearing loss in midlife increased the risk of dementia by twice as much as any other single factor.

As I often explain in these pages, this doesn’t prove it’s the hearing loss that brings on dementia. Both conditions could be brought on by some third factor not identified. Just as an example, there might be a virus or a gene that causes hearing loss and dementia.

But the Lancet findings – and much other evidence — makes it important to establish if poor hearing is a genuine risk factor because it’s something that can easily be set right in most people. Modern hearing aids are very good at improving hearing even if it’s not possible to restore it fully.

To find out more, researchers at the University of Exeter and Kings College London made use of the 25,000 volunteers who are taking part in an ongoing online project called PROTECT.

This analyzes the health of people aged 50 or over who have not been diagnosed with dementia. Researchers hope to find the factors that affect how the brain ages. Participants also provide a sample of DNA through a simple at-home kit.

Among the whole group, 4,372 reported hearing problems but only 1,557 wore hearing aids. The researchers found those wearing hearing aids had better working (short-term) memory and aspects of attention, including faster reaction times – a measure of concentration – than those who didn’t get treatment.

Protects the Brain

Study leader Dr. Anne Corbett said, “Our work is one of the largest studies to look at the impact of wearing a hearing aid, and suggests that wearing a hearing aid could actually protect the brain.”

Another member of the team, Professor Clive Ballard, added, “This is an early finding and needs more investigation, yet it has exciting potential. The message here is that if you’re advised you need a hearing aid, find one that works for you. At the very least it will improve your hearing and it could help keep your brain sharp too.”

The findings of this study, which has yet to be published, have been positively received.

Dr. Llwyd Orton, Lecturer in Neurophysiology, Manchester Metropolitan University, enthused, “This is an exciting preliminary finding…,” and Dr Jana Voigt, Head of Research, Alzheimer’s Research UK, reacted with almost the same words.

The reason why hearing loss is linked to cognitive decline is not yet known. It could be biological or social. It may harm the brain in some way or it could leave people feeling socially isolated or cause them to become depressed, both of which are risk factors for dementia in themselves.

Meanwhile, hearing is not the only sense we need to be concerned about.

Combined Disabilities Multiply the Risk

At the Alzheimer’s Association International Conference in Los Angeles in July, scientists from the University of Washington reported on their study into the effect of both hearing and visual impairment in 2,051 people aged 75 or older.

Over seven years they found a reduction in either of these senses increased the risk of Alzheimer’s by ten percent. But impairment in both at once more than doubled the risk to 112%.

In another presentation, researchers at the University of California, San Francisco studied the combined effects of partially losing the senses of sight, hearing, smell and touch.

Of the 1,810 participants aged 70 to 79, those in the bottom quarter of function had almost seven times the risk of dementia compared to those in the highest quarter.

But even mild impairment in all four senses was linked to a more-than-two-thirds higher risk of dementia.

  1. http://www.exeter.ac.uk/research/newsandevents/news/title_725112_en.html
  2. https://www.alz.org/aaic/releases_2019/sunSENSORY-jul14.asp