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Hearing loss is a widespread issue among older adults, with nearly 60% of individuals aged 60 and over experiencing moderate or greater hearing impairment. As age increases, so does the prevalence of dementia, disproportionately affecting women. In Australia, for individuals aged 90 and above, women are 1.4 times more likely than men to be diagnosed with dementia. In 2023 alone, an estimated 411,100 Australians were living with the condition, a number projected to more than double by 2058.
The Link Between Hearing Loss and Dementia
Cognitive decline is a natural part of aging, but research indicates that older adults with untreated hearing loss experience a faster rate of cognitive decline and are at greater risk of developing dementia. The risk increases with the severity of hearing loss, with those suffering from severe-profound hearing loss—who gain little benefit from hearing aids—being at the highest risk.
Despite the significant impact of hearing loss on quality of life, fewer than 10% of eligible individuals opt for cochlear implants. While it remains unclear whether hearing loss directly causes dementia or is merely associated with it, one possible explanation is that hearing loss contributes to social isolation. This, in turn, reduces brain stimulation and weakens cognitive reserve, the brain’s ability to maintain function despite aging and disease.
Building Cognitive Reserve
Cognitive reserve plays a crucial role in maintaining brain health. People with high cognitive reserve can sustain normal cognitive function even in the presence of risk factors such as genetic predispositions, cardiovascular disease, or hearing loss. Engaging in activities such as regular exercise, maintaining a healthy diet, moderate alcohol consumption, sufficient sleep, social engagement, and cognitive stimulation (such as puzzles and crosswords) can help strengthen cognitive reserve.
Though it is unknown whether restoring hearing via cochlear implants directly boosts cognitive reserve, researchers believe there may be a window of opportunity to restore hearing and slow the progression of cognitive decline.
The COCHLEA Study
Since 2016, the COCHLEA (Cochlear implant Outcomes and Cognitive Health—Longitudinal Evaluation of Adults) study has been investigating this potential link. Conducted in collaboration with the Royal Victorian Eye and Ear Hospital, the Mater Hospital, and the AIBL (Australian Imaging, Biomarkers & Lifestyle Flagship Study of Aging) at the Florey Institute of Neuroscience and Mental Health, the study compares cognitive performance between individuals with cochlear implants and those without hearing aids or cochlear implants.
Over four and a half years, researchers assessed participants aged 60 and above at 18-month intervals using computerized card games to measure cognitive function. Findings indicate that individuals with cochlear implants showed improvements in executive function and working memory, while their cognitive performance remained stable overall. In contrast, participants without cochlear implants or hearing aids exhibited significant declines in two of the four cognitive functions assessed, despite having better hearing.
Executive functions—such as decision-making, planning, and problem-solving—are crucial for daily life, while working memory helps retain and process information. The sustained improvement in these cognitive functions among cochlear implant users suggests a potential protective effect against cognitive decline.
Promoting Healthy Aging
It is rare to observe cognitive improvement in aging adults, making the COCHLEA study’s findings particularly significant. Even individuals with normal hearing typically experience cognitive decline over time. These results suggest that cochlear implants may not only enhance communication and quality of life for individuals with severe-profound hearing loss but also promote healthy aging by improving and maintaining cognitive function.
Given the potential benefits, experts recommend scheduling a hearing test for individuals experiencing hearing difficulties. Early intervention could play a crucial role in mitigating cognitive decline in later years. The COCHLEA study continues to welcome adults aged 60 and over who qualify for cochlear implants to participate in ongoing research.
Disclaimer:
The findings of the COCHLEA study provide promising insights into the potential cognitive benefits of cochlear implants. However, further research is required to establish a direct causal relationship between hearing restoration and cognitive decline prevention. Individuals concerned about hearing loss or cognitive health should consult a medical professional for personalized advice.
