Tom Dening: Hearing aids and cognitive impairment

Summary

For people who are accustomed to hearing, changes in hearing ability can significantly impact an individual's communication and social life. In this blog, Professor Tom Dening discusses his recent experience of getting hearing aids, using this to reflect on the complicated relationship between hearing loss and dementia.

My hearing’s going. It really is. How long? Impossible to say, as it is an insidious change. More than a year, probably. Subtle changes, for example, everyone else sets the TV volume at about 8 and I have it at 11 or 12, with the subtitles on for everything except the news. I complain about how actors mumble, especially American ones. Actually, they do, that isn’t just hearing loss. Social conversations start to become hard work as I can’t always follow, so I often give up trying. At work, remote meetings are fine because you can turn up the volume on Teams or Zoom, but face to face is different because people are at different angles and you can’t adjust their volume controls. I become aware that I am more often asking people to repeat themselves. I suspect my right ear is worse as having conversations in a car when I am a passenger are more difficult than when I am driving. The subtlety of music in the car is lost beneath the rumbling of the wheels.

Hearing loss and dementia have a complicated relationship and the joint topic has been the subject of increasing research interest. There are two main aspects: hearing loss as a risk factor for dementia and the challenges of comorbid hearing loss with dementia. Hearing loss from mid-life has been identified as probably the largest potentially modifiable risk factor for subsequent dementia, contributing nearly 10% of the population risk. This often gets translated into hearing loss causes 9% of cases of dementia, but that’s not how it works: it’s the proportion of the risk that is due to hearing loss. Nonetheless, miraculous abolition of hearing loss would significantly reduce the number of cases of dementia by at least delaying its onset. Second, dementia and hearing loss are both common conditions in older people and their prevalence increase with advancing age. In certain populations, notably care home residents, both conditions are almost ubiquitous. Having hearing loss on top of dementia compounds many of the problems that can arise and further challenge a person’s independence, well-being and social life.

Once I start to think that something needs doing, it really does. So, off to the audiologist. I spend some time in headphones, pressing a button whenever I think I hear beeps of varying frequency and decreasing volume. This is hard. I am aware that I am doing badly as there are long pauses of apparent silence. Concentration wavers, at one point I think I am starting to hallucinate. She shows me my audiogram, which looks like someone falling off a cliff. ‘You aren’t hearing higher frequency sounds like S or F or Th, so your brain is having to work hard to fill the gaps for you. For someone with this pattern, I would recommend hearing aids.’  A feeling of resignation and inevitability descends over me. Okay, let’s go for it, after all I do have a real problem. We discuss links between hearing loss and how treatment helps not only hearing but brain health. I don’t reveal immediately that this is an area of my research interest.

It’s a moot point, how good is the evidence that intervention for hearing loss (hearing aids) modify the risk of subsequent dementia? Certainly, cohort studies show that people with established hearing loss have an increased risk of developing dementia, but the mechanisms of this are not clear. Hypotheses include that there may be a common pathology underlying both conditions or else the social withdrawal resulting from hearing problems may in itself cause accelerated cognitive decline from lack of stimulation. Trials are underway to assess whether hearing aids are effective in reducing dementia risk but the problem is that it’s not ethical to have a placebo group with dud devices, so you can’t do a randomised controlled trial of the necessary duration. There does seem to be better evidence, though, that hearing aid use is associated with improved mood and well-being, so these seem like useful outcomes anyway.

Three weeks later, I’m back to get the aids fitted. This is fascinating as the audiologist is able remotely to adjust the frequencies that the devices amplify. As they are turned on, I am aware of higher frequency sounds, rustling paper, slapping sounds of running water and so on. Importantly, I can once again discern higher frequencies against background noise, so the car radio is once again pleasurable and I can hear 3- or 4-person conversations much more easily. I take ridiculous pleasure in connecting to all the Bluetooth devices in and around the home. The iPad is brilliant as I can carry it round with me and catch up on the late-night Radio 3 programmes that I usually miss. Am I cognitively sharper? Hard to tell. My wife thought so. She also thought I was smiling a lot and enjoying the new experience. Maybe I am less tired at the end of a working day but it’s hard to be sure. At follow-up appointment, I am raving about the hearing aids, much to the pleasure of the audiologist. She tells me that men take an average of 2 years from having an assessment to accepting wearing hearing aids, so I have been unusual in that respect. I feel a little self-congratulatory, I confess. We all like praise.

Great! I don’t like to take them out at night and I delight in putting them in when I get up. I am quite happy to be an advocate for hearing aid use. I have already agreed to help one research study as a user, which seems like fun. Do I believe I am reducing my dementia risk? Not sure, actually I am a bit fatalistic about whether I will get dementia or not. However, (1) I will accept the current benefits in terms of improved hearing and being able to do my job properly and (2) I am certainly not increasing my dementia risk, so if I am actually reducing it, that’s a welcome bonus too.

With thanks to Kirsty Davison, audiologist, and my colleagues in hearing science.

Tom Dening
School of Medicine, University of Nottingham
October 2022

Interested in reading more? You can read more blog posts from Tom and others on the fantastic Dementia Day-to-Day and Institute of Mental Health blogs.

Guest contributor: Tom Dening, MA MD PhD FRCPsych