April 17, 2025

expert reaction to study on population attributable fraction of incident dementia associated with hearing loss

A study published in JAMA Otolaryngology–Head & Neck Surgery looks at dementia associated with hearing loss.

Prof Jason Warren, Professor of Neurology and Consultant Neurologist, UCL, said:

“Dementia in older people. Importantly, the study advances previous work in this area by attempting to include a more diverse older population and to distinguish between objectively measured and self-reported hearing problems. It is particularly interesting that people who complained of hearing problems did not have an increased dementia risk. This underlines the need for hearing tests when assessing dementia risk, but also suggests that lack of awareness of hearing difficulties might itself be an early warning signal for dementia. While more work is needed to establish to what extent hearing aids might delay dementia, studies of this kind support the view that we should protect hearing to protect brain function.”

Dr Isolde Radford at Alzheimer’s Research UK, said:

“There’s strong evidence linking hearing loss in mid to later life with an increased risk of dementia. We don’t yet know if hearing loss directly causes dementia or whether it causes other conditions that, in turn increase our risk. But this study adds to the link between hearing loss and dementia, and offers further evidence of the value of investigating hearing loss interventions as a potential measure to protect brain health.

“This research looked at nearly 3,000 adults aged 45 and over in the U.S. to explore links between hearing loss and dementia. However, because participants were all from the same area and identified as either Black or White, the findings might not reflect wider trends across the U.S. or globally. The study also relied on some people reporting their own hearing loss, which can be inaccurate, possibly due to stigma, so future research should use proper hearing tests to get a clearer picture.

“What we do know is that hearing loss, like dementia, isn’t an inevitable part of ageing. That’s why we’re calling on the government to include a hearing check in the NHS Health Check for over-40s. This simple step could help millions identify hearing loss earlier and take appropriate action, such as wearing hearing aids, that may help reduce their risk of dementia.

“With around one million people living with dementia and 12 million affected by hearing loss in the UK, we urgently need more research to better understand the link, and identify who would benefit most from simple interventions like hearing aids. This insight is vital to help health services deliver the right support to the right people.”

Dr Coco Newton, Visiting Research Fellow, University of Cambridge, said:

“This study confirms that hearing loss is having a uniquely negative impact on people’s future risk of dementia, even well into older age. The authors controlled for any potential confounding effects from other dementia risk factors such as lower education, smoking, poorer heart health, diabetes, or genetic risk. However, how well hearing aid use can compensate for this increased risk remains an open question – around half of this study population with hearing loss used a hearing aid, and they only had a modest benefit. It could be that we need to follow up them up for longer than 8 years to truly measure the effect of hearing aid use.”

Prof Masud Husain, Professor of Neurology, University of Oxford, said:

“These results add to growing evidence that hearing loss is associated with increased risk of dementia. Exactly how is the subject of an interesting debate.

“The most striking feature of the findings is that while hearing loss established using objective hearing tests (audiometry) shows a relationship to dementia, self-reported hearing loss does not. This seems to because people do not reliably know – or acknowledge – that they have hearing impairment.”

Dr Thomas Littlejohns, Senior Epidemiologist, Nuffield Department of Population Health, University of Oxford, said:

“There has been a lot of interest recently on whether hearing problems are linked to a higher risk of developing dementia. If so, this would be a highly promising way of reducing dementia risk as hearing problems are common at older ages, and often treatable.

“This paper uses a population of 3,000 US-based adults with an average age of 75 to estimate how many cases of dementia in this particular sample might be due to hearing problems. The authors do this using a statistical method known as a Population Attributable Fraction (PAF). A PAF is an equation which combines information on 1) the percentage of people with hearing problems and 2) the strength of association between hearing problems and dementia to estimate how many dementia cases are due to hearing problems. Or to put it another way, if hearing problems ceased to exist then the PAF is the percentage of dementia cases that would also be eradicated. In this paper, the authors find that this could be as many as 1 in 3 dementia cases, a substantial number.

“However, it is crucial to note that this assumes a causal relationship, and because this paper uses observational data it does not provide any evidence on whether hearing impairment causes dementia. For example, we can’t tell from these results whether hearing problems are related to dementia through other factors common to ageing or whether hearing problems are a consequence, rather than a cause, of dementia. The latter is a particular problem in observational data, as dementia develops over many years and it is possible that hearing problems emerge in the early stages of dementia (similar to memory problems) before a clinical diagnosis is made. Nevertheless, this paper is well-designed and provides useful information on how many dementia cases hearing problems might cause, but only if we know the relationship is causal, which we cannot tell from this study.”

‘Population Attributable Fraction of Incident Dementia Associated With Hearing Loss’ by Emily Ishak et al. was published in JAMA Otolaryngology–Head & Neck Surgery at 16:00 UK time on Thursday 17^th April. 

DOI:10.1001/jamaoto.2025.0192

Declared interests

Dr Coco Newton: No direct industry funding or links, but my funders include Alzheimer’s Society, ARUK, and Alzheimer Scotland if relevant. I once worked on a study part funded by Merck SP but the grant wasn’t in my name.

Dr Thomas Littlejohns: None to declare

Prof Masud Husain: I have no conflicts of interest.

For all other experts, no reply to our request for DOIs was received.