July 15, 2019

expert reaction to a conference poster on hearing aids and dementia risk

Research presented in a conference poster at the Alzheimer’s Association International Conference, reports that use of hearing aids in older adults can maintain brain function over time, compared to those that do not use them.

Dr Llwyd Orton, Lecturer in Neurophysiology, Manchester Metropolitan University, said:

“This is an exciting preliminary finding that suggests that people with age-related hearing loss, may mitigate against cognitive decline by wearing hearing aids. The recent Lancet report found that mid-life hearing loss increased dementia risk by double any other single factor, including smoking and obesity, though this is now widely known. One argument against an association between hearing loss and cognitive decline is that no such associations are apparent in people with hearing loss early in life. That benefits were found in people with age-related hearing loss, the most common form or hearing loss, suggests that hearing aids can be of benefit beyond just improving hearing, in the most affected patient group. There are however, important unanswered questions to be addressed, such as what mechanisms led to these improvements, such as reduced social isolation, reduced cognitive load, or physical changes within the ear and brain. A reason hearing aids may work in this patient group is that losing hearing function later in life is socially isolating, while younger people develop sign language and social groups where communication is not dependent on sound.

“Another consideration is that the majority of people who are fitted for hearing aids, do not wear them correctly. This may lead to selection biases in studies such as these, including socioeconomic factors, due to the high cost of hearing aids and personal issues, such as embarrassment, which are common. I would agree with the statement that we need RCTs to test alternative explanations and identify potential mechanisms that link hearing loss to increased dementia risk.”

Dr Martin Coath, Associate Lecturer, Plymouth University, said:

“Hearing loss is a type of social isolation as, for example, it can make following conversations in a noisy room a struggle. Those with hearing issues who choose to use high-quality hearing aids are likely to continue to enjoy social experiences and conversations whereas those who do not use a hearing aid may choose to experience fewer social and sensory interactions as they are more challenging. Therefore, one possible reason why this early stage study sees a link between hearing aid use and better brain function is that those using a hearing aid are staying engaged and actively interested in all manner of sensory and social experiences. It may be that when the full study is published the data will show that more or less anything you can do to support continued physical and intellectual activity with age will have some measurable protective effect on brain function.”

Dr Jana Voigt, Head of Research, Alzheimer’s Research UK, said:

“There is a growing link between hearing loss and brain function, with hearing loss being a suggested risk factor for dementia. This large-scale study indicates that wearing hearing aids could boost aspects of memory and attention in healthy older people, but it remains to be seen whether this can reduce the risk of developing dementia.

“This is an exciting result that will need to be further tested in clinical trials, and if shown to work, encouraging people to wear hearing aids could be a simple but effective way of reducing dementia risk. At this point, it’s unclear what is driving the link between hearing loss and dementia, and this is why Alzheimer’s Research UK have teamed up with Action on Hearing Loss to fund projects to unpick the biology of this link.”

Dr Rebecca Dewey, Research Fellow in Neuroimaging, University of Nottingham, said:

“As the press release states, it is early days and the results are preliminary. These findings need to be tested using clinical trials to really pin down the science and find out why and how this relationship between hearing aid use and dementia risk exists.

“Although this research is early stage, it agrees with a lot of smaller-scale studies that have already been published. A lot of people have been saying this for a long time. A lot of research undertaken independently around the world agrees with the message that hearing aids are beneficial cognitively for those who need them, and that too much of the time hearing aids sit in a drawer, to the disadvantage of the person. An online study of 25,000 people over 50 is very large and very compelling. With this knowledge, the group will be in a good position to design a randomised control trial to test the why and the how.”

“We currently don’t know much about whether this link between hearing aids and brain function is cause or effect. Does hearing loss worsen the decline in brain function and does treating hearing loss slow or prevent this cognitive decline? Or alternatively, are hearing loss and cognitive decline linked in some other way, for example, there may be some other factor that causes or worsens both hearing and brain function.”

* The poster entitled ‘Use of Hearing Aids in Older Adults with Hearing Loss Is Associated with Improved Cognitive Trajectory’ was presented at the Alzheimer’s Association International Conference Los Angeles, USA on Monday 15^th.

Declared interests

None received.