MELBOURNE, AUSTRALIA — As the global population continues to age, the prevalence of age-related hearing loss and dementia is rising rapidly. Hearing loss is currently considered the largest potentially modifiable risk factor for dementia. However, the impact of hearing interventions like hearing aids on cognitive function has remained unclear, with conflicting evidence from previous studies.
New findings from a prospective longitudinal study suggest that using hearing aids may help delay cognitive decline and the onset of dementia in older adults with hearing loss.
The research, conducted by investigators at the University of Melbourne in Australia and recently published in the journal Frontiers in Neuroscience, sheds light on the potential benefits of hearing aid use.
ENHANCE Study: Exploring Hearing Loss, Hearing Aids and Cognitive Function
The study, called ENHANCE, compared cognitive outcomes over three years between two groups – a group of first-time hearing aid users aged 60 and older with mild to severe hearing loss, and a group of older adults from the Australian Imaging, Biomarkers and Lifestyle (AIBL) study, some with untreated hearing loss and some with normal hearing.
At baseline before being fitted with hearing aids, the hearing aid group scored significantly worse on cognitive tests assessing working memory, visual attention, visual learning and psychomotor function compared to the AIBL group. However, after three years of hearing aid use, the trajectory changed dramatically.
The hearing aid group demonstrated overall cognitive stability, showing no significant decline except on one psychomotor test, and declining at a significantly slower rate than would be expected for the general older adult population. In contrast, the AIBL group experienced significant cognitive decline in working memory, visual attention and psychomotor function over the same time period.
The findings remained consistent even after controlling for factors like education level and physical activity that can impact cognitive performance. The results indicate hearing intervention with hearing aids may be a useful strategy for reducing the global burden of dementia, which currently has no cure.
Around 40% of dementia cases are thought to be preventable by modifying risk factors, and hearing loss is considered the largest modifiable risk factor. Simply providing hearing aids and ensuring they are worn could be a safe, effective and non-invasive way to potentially delay cognitive decline for millions of older adults worldwide.
There are several proposed theories for why treating hearing loss with hearing aids could benefit cognition. One is the “use it or lose it” theory – that decreased auditory stimulation to the brain from hearing loss may cause changes in brain structure and function over time. Another theory suggests people with untreated hearing loss expend more cognitive resources on auditory processing, leaving fewer resources for other cognitive functions like memory.
Being able to hear clearly again through hearing aids may free up cognitive resources that can then be used for other processes. It may also help re-engage the auditory regions of the brain that were underutilized due to hearing loss.
Further Research Needed
While the initial ENHANCE study results are promising, the researchers emphasize that further investigation with larger sample sizes and longer follow-up is still needed. The study is ongoing, and they hope to gain more insights into questions like:
- How long can the cognitive benefits of hearing aid use be sustained?
- Can hearing aids not only delay decline, but improve cognition?
- Does more daily hearing aid usage provide greater cognitive benefits?
- How do hearing aids impact other risk factors for dementia like social isolation?
- Hearing aids promote healthy aging and overall wellbeing in many ways beyond just cognitive function. They allow people to stay socially connected, which is crucial for cognitive health as well as quality of life. They reduce risk of issues like falls, depression and hospitalization.
Despite the benefits, over 70% of those who could benefit from hearing aids do not use them currently. The researchers hope studies like ENHANCE will increase awareness of the growing links between hearing loss, cognitive decline and dementia risk.
This preventative step is best taken before hearing loss starts to majorly impact brain function, when the brain still has flexibility to adapt to restored hearing input. Identifying and treating hearing loss early through regular screening may be key for maximizing the cognitive benefits of hearing aids and supporting healthy aging.
As a safe, accessible and relatively low-cost intervention, hearing aids could potentially play a major public health role in addressing the impending dementia crisis if the cognitive impacts are further validated through continued research. For now, the ENHANCE study contributes important evidence that audiology and hearing care may be critical pieces of the prevention puzzle.
Reference:
- Sarant, J. Z., Busby, P. A., Schembri, A. J., Fowler, C., & Harris, D. C. (2024). ENHANCE: A comparative prospective longitudinal study of cognitive outcomes after 3 years of hearing aid use in older adults. Frontiers in Aging Neuroscience, 15. https://doi.org/10.3389/fnagi.2023.1302185
