Feb 2021 RACGP GPNews
But it’s not all bad news. Study co-author Professor Henry Brodaty speaks to newsGP about how GPs can help patients be proactive.
In Australia, hearing loss affects 74% of people aged over 70, and has been identified as one of 12 lifestyle risk factors that account for 40% of dementia cases. But now researchers have confirmed, for the first time among Australian cohorts, just how significant the association is between self-reported hearing loss and mild cognitive impairment, a precursor to dementia. The research draws on the first six years of data from the Centre for Healthy Brain Ageing’s (CHeBA) Sydney Memory and Ageing Study from 2005–2017, involving 1037 Australian men and women aged 70–90.
Participants underwent detailed neuropsychological and clinical assessments every two years and were categorised into one of four groups: no problems, mild problems, or moderate to severe.
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 or dementia at their six year follow-up.
Scientia Professor Henry Brodaty, co-director of the CHeBA at the University of New South Wales, was a co-author on the study. ‘We found that at baseline, people with moderate to severe hearing performed worse than the people who had no or mild hearing problems,’ he told newsGP. ‘Over six years, there was a 60% greater risk of developing mild cognitive impairment or dementia, and looking at continuous data at the neurocognitive performance on testing, there was substantially greater deterioration in the moderate to severe group than in the other two groups. ‘So everyone declined a little bit, even the people with no hear loss, but the people who had moderate to severe declined significantly more.’
But it’s not all bad news. According to a 2017 report published in The Lancet, addressing midlife hearing loss may prevent up to 9% of new dementia cases. ‘There have been studies since that review … looking at the effects of hearing aids, and findings that that risk is ameliorated,’ Professor Brodaty said. ‘One of the potential mechanisms that this may play a part in is that people with hearing loss tend to withdraw socially, as it can be difficult in a group to hear things. But we know that people who are more socially engaged … have a lower risk of dementia than people who are socially isolated.
‘So we’d encourage people to get hearing aids. ‘However, those of us who work clinically – and most GPs will know this – find that if you get people who are over 80 needing hearing aids, it doesn’t work too well, because they don’t like using them. [For instance] my mother. We spent several thousand dollars on her hearing aid, and it lived very comfortably in a drawer by her bed.
‘But the earlier people start using the hearing aid, the more likely they are to continue using it and to get the benefits from it.’
Scientia Professor Henry Brodaty, study co-author and co-director of the CHeBA, says when it comes to dementia risk factors, being proactive can go a long way
One identified weakness of the study is that it is based on self-reported hearing loss. As the study has progressed however, researchers have started to measure participants’ hearing using audiometers, which they plan to analyse in future. What Professor Brodaty is keen to make clear is that hearing loss is only an ‘associated’ dementia risk. ‘We know that for older people in the community, their greatest fear used to be cancer – not the economy, not the pollution, not global warming – but now, it’s dementia. People are terrified,’ he said. ‘But we’re not saying people with hearing loss are going to get dementia. That’s a really important message to get across because the majority of people over a certain age will have some hearing problems. ‘We’re saying that there’s an increased risk. For example, if the risk of having dementia in your 70s is 10%, and you have a 60% increased risk [due to hearing loss], you risk is still 16%. So the absolute increase is small.’
Aside from encouraging the use of hearing aids, where appropriate, Professor Brodaty says there are a number of things GPs can do to help their patients be proactive against cognitive decline.
‘If there are any symptoms of memory loss, GPs should be testing for cognition,’ he said. ‘Mini-mental is the one that’s most commonly used, but it’s a bit weak, particularly in frontal executive function. So the MoCA may be a better example, or the one we developed, the GPCOG, is quicker than the Mini-mental and performs slightly better. ‘They should also look at all the modifiable risk factors – is a person physically active? Are they obese? Do they have type 2 diabetes? If they have high blood pressure in midlife, should that be treated? Are they a smoker? Any heavy alcohol use?
‘And GPs should be thinking about doing this for themselves, it’s not just for the patients.’
While there is no magic bullet to prevent the onset of dementia entirely, Professor Brodaty says being proactive may prove to be just as effective as if there were one. ‘What we’re trying to do is at least delay the onset of it, because it’s mainly a disease of late life,’ he said. ‘The risk doubles every five years. So if you can delay it for five or 10 years, for many people, that’s going to be delaying it until after they die.’