New research has uncovered an Australian-first association between the impact of hearing loss on cognitive abilities and an increased risk for dementia.

In Australia, hearing loss affects 74% of people aged over 70. International studies estimate that people with severe hearing loss are five times more likely to develop dementia. Addressing midlife hearing loss could prevent up to 9% of new cases of dementia – the highest of any potentially modifiable risk factor.

Lead author at Macquarie University’s Department of Cognitive Science, Dr Paul Strutt, told HealthTimes that while more studies were needed to better understand the biological pathways underlying the link, there was a prevailing theory.

“One of main positions is that hearing loss – particularly occurring in midlife – can lead to an increased risk of social isolation and depression in older age, and we know that independent of hearing loss, these are both factors for dementia in older age.”

“And also, if you’re thinking about the effects of hearing loss over time, when you’re cut off from people around you and not socialising as regularly, then you’re not getting the same amount of regular cognitive stimulation, and so brain is missing out on that really important stimulus.”

Led by a research collaboration between the Centre for Healthy Brain Ageing (CHeBA), UNSW Sydney and Macquarie University’s Centre for Ageing, Cognition and Wellbeing, this research was based on a six-year study of older Australians in CHeBA’s Sydney Memory & Ageing Study from 2005-2017.

Individuals who reported moderate-to-severe hearing difficulties had poorer cognitive performances overall, particularly in the domains of Attention/Processing Speed and Visuospatial Ability. They also had a 1.5 times greater risk for mild cognitive impairment (MCI) or dementia at the 6 years’ follow up.

Co-Director of the CHeBA and co-author, Professor Henry Brodaty, said the study was the first of its kind to identify the relationship between hearing loss and risk for mild cognitive impairment or dementia in a large Australian-based study of
older adult men and women.

“The findings contribute to the evidence base providing support for a study looking at the effect of hearing devices on cognitive function,” said Professor Brodaty.

Dr Strutt said while the results were significant, it’s important for people not to be alarmed.

“Most adults over 70 have hearing loss (almost 3 in 4), but only about 1 in 10 adults in their 70s have dementia. Hearing loss increases the risk by 60%.”

“So, in an absolute sense, hearing loss increases risk to 16% – it is not a 1:1 causal link.”

“The really positive thing [to come out of this study] is that it gives us a powerful window into looking at treatments for a modifiable risk factor for dementia.”

“And this is a lifestyle risk factor that people can be proactive about and can control by seeking hearing treatment and getting the benefit of that as soon as possible”, Dr Strutt said.

Professor Brodaty added that “studies are now emerging that hearing aids may reduce this risk.”

“Large, multi-centre trials examining the wide-ranging benefits of hearing interventions in older adult populations with hearing loss could determine the potential for risk reduction associated with this significant and modifiable risk factor for MCI and dementia in older age,” Professor Brodaty said.

Dr Strutt believed that this most recent piece of research underscores the crucial role that modifiable lifestyle risk factors play in dementia.

“I think we need to start thinking about hearing loss in the same way as we might think about other potentially-modifiable risk factors for dementia.”

“Making healthy lifestyle choices like regular physical exercise, maintaining a healthy diet, and controlling medical conditions like high blood pressure and cholesterol, and diabetes, and not smoking are all things that can reduce an individuals’ risk for dementia.”

“These are proactive steps that people can make, not only to reduce their risk of dementia, but also to enjoy a better quality of life.”

“Treating hearing loss should be thought about in the same way – so if someone thinks they might be having hearing difficulties, I would encourage them to discuss their concerns, initially with their GP, and to seek professional assessment by an audiologist.”