Hearing Loss May Play A Larger Role In Dementia Than Previously Thought – OpEd

Nearly 1 in 3 dementia cases linked with audiometric hearing loss- a new study. If the association between hearing loss and dementia is causal, up to 32% of population-level dementia risk could potentially be delayed or prevented if we completely treat  hearing loss. 

A recent issue of the JAMA Otolaryngology-Head &Neck Surgery journal (17 April 2025) published a new, highly relevant and important study with beneficial impact on aging populations. Researchers knew that hearing loss treatment delays cognitive decline in high-risk older adults. However, they did not know the preventive potential of addressing hearing loss on incident dementia in a community-based population of older adults, and whether it varies by the method of hearing loss measurement. In this study. they calculated the population attributable fraction (PAF) of incident dementia associated with hearing loss (HL) in older adults and investigated the differences by age, sex, self-reported race, and method of hearing loss measurement.If the association between hearing loss and dementia they found is causal, up to 32% of population-level dementia risk could potentially be delayed or prevented if we completely treat hearing loss. 

 The study concluded thus (verbatim): 

1. In a large cohort of community-dwelling older adults with a mean age of 75 years, nearly 1 in 3 incident dementia cases could be attributed to clinically significant Hearing Loss (HL).  
2. Self-report substantially underestimated HL prevalence and was not associated with any dementia incidence.  
3. Interventions for sensory health in late life might be associated with a broad benefit for cognitive health. 

The researchers suggested that future studies should give priority to objective measures of hearing loss over subjective measures to quantify its preventative potential on dementia risk. 

Importance of Dementia

According to the WHO, Dementia is not a single disease but rather a general term for a group of illnesses that negatively affect the brain. These illnesses primarily impact a person’s memory, thinking, and their ability to perform everyday activities. The WHO identified 12 risk factors such as Age, High blood pressure (hypertension), High blood sugar (diabetes), Being overweight or obese among others. Dementia has a wide-ranging impact, not only on the individuals living with the condition but also on their carers, families, and society as a whole. The WHO estimated that in 2021, 57 million people worldwide had this disease. The researchers’ study on Dementia (the 7^th killer globally) has top priority 

In their present paper, the authors waxed eloquent on the strengths of the study and described its limitations. Interestingly, several specialists reacted to the study with commendable alacrity; may be because it is an important study. 

Hearing aids are very expensive. A decent pair is already beyond the reach of common man. I hope that hearing aid industry will not exploit the situation. A critical appraisal of the comments including the weaknesses of the study, under calm contemplation shows that exaggerated hype on the study is neither warranted nor justified in view of unknown factors!

The Study 

The research was part of the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS). 

[ARIC is designed to investigate the causes of atherosclerosis and its clinical outcomes, and variation in cardiovascular risk factors, medical care, and disease by race, gender, location, and date. To date, the ARIC project has published over 800 articles in peer-reviewed journals.]

The present study included researchers from 4 ARIC field centres. They were from the Universities of Columbia, Vanderbilt, New York, Maryland Minnesota, New York and Johns Hopkins The participants were community-dwelling older adults aged 66 to 90 years without dementia at baseline who underwent a hearing assessment at ARIC-NCS visit 6 (2016-2017). The study had up to 8 years of follow-up (2011-2019). Data analysis took place between June 2022 and July 2024.

Results

 Among 2946 participants of mean age 74.9, 1751 were female; 637 Black and 2309 White. 1947 participants had audiometric hearing loss, and 1097 had self-reported hearing loss. The population attributable fraction of dementia from any audiometric hearing loss was 32.0%; Population attributable fractions were similar by hearing loss severity mild HL: 16.2%; moderate or greater HL:16.6%.

Self-reported hearing loss was not associated with an increased risk for dementia, so the population attributable fraction was not quantifiable. Population attributable fractions from audiometric hearing loss were larger among those who were75years and older (30.5%), female (30.8%) and White (27.8%), relative to those who were younger than 75 years, male, and Black.

The findings mean that “up to 32% of population-level dementia risk could potentially be delayed or prevented if we completely treated hearing loss, assuming there is a causal association between hearing loss and dementia,” Med Page Today (17 April 2025) quoted one of the lead authors Jason Smith, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland. “It implies there could be broad benefits for dementia prevention with interventions for this risk factor even in later life.”

The PAF (the maximum proportion of dementia that could be attributed to hearing loss in a population) of 32% in this study was substantially higher than other estimates. The 2020 Lancet Commission on Dementia Prevention  reported a global PAF of 8.2% for hearing loss, for example.

One reason for the wide variance “is that we measured audiometric hearing loss,” Jason Smith told Med Pagé Today. “Some prior PAF research has measured hearing loss using self-report. Self-report underestimates hearing loss prevalence in older adults — it is likely capturing a separate, distinct construct — and, by extension, could underestimate the PAF

Expert reaction to the study 

(Science Media Centre. London published a press release containing expert reactions on the study)

Prof Jason Warren, Professor of Neurology and Consultant Neurologist, UCL noted that 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.” He added.

According to Dr Isolde Radford at Alzheimer’s Research UK,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.”, she clarified

“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 Radford lucidly highlighted the importance of supporting more research in this field.

After listing important features of the study, Dr Coco Newton, Visiting Research Fellow, University of Cambridge raised an interesting issue. “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 agreed that these results add to the growing evidence that hearing loss is associated with increased risk of dementia. 

“Exactly how is (this) the subject of an interesting debate”, he added.

“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.”, he cautioned.

Dr Thomas Littlejohns, Senior Epidemiologist, Nuffield Department of Population Health, University of Oxford argued that 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.”He clarified 

The most important take away from this study is that if the association between hearing loss and dementia is causal, up to 32% of population-level dementia risk could potentially be delayed or prevented if we completely treat hearing loss.