Hearing impairment is considered a part of ageing and is one of the most common sensory impairments in old age. Dementia is also emerging as as major health concern among older people. Dementia is characterised by progressive deterioration in cognitive function such as memory and decision making.
A recent study published in JAMA Network Open investigated the relationship between hearing loss, brain structure, cognitive performance, and dementia risk using data from the long running Framingham Heart Study. The participants underwent a detailed hearing assessments, brain magnetic resonance imaging (MRI), and cognitive testing.
Key findings of the study
Changes in brain structure
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Individuals with mild or greater hearing loss were found to have smaller total brain volumes
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Increased white matter abnormalities compared to the individuals with normal hearing.
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These structural differences are often considered markers of brain ageing and are commonly linked with neurodegenerative conditions.
Increased risk of dementia
The researchers found that participants with hearing loss had approximately a 71% higher relative risk of developing dementia compared with those with normal hearing.
Genetic influence
Another finding was that the association between hearing loss and dementia was particularly strong among individuals carrying the APOE ε4 genetic variant, which is known to increase the risk of Alzheimer disease.
How hearing loss can impact the brain
Increased cognitive load
When hearing becomes difficult, the brain works harder to process sounds. The brain has to exert more to process degraded sounds, leaving less capacity for memory and thinking.
Reduced stimulation
Over time, reduced sound input may also affect how certain brain regions function, similar to how a muscle weakens when it is used less.
Social isolation
Hearing loss also leads to less social interactions. Struggling to follow conversations may lead to withdrawal, loneliness or depression, all of which are linked to higher risk of dementia.
Although research shows a strong association between hearing loss and dementia, hearing impairment should not be considered a direct cause of dementia, it is one of the several factors that contribute to the cognitive decline. Early screening, greater awareness, and effective management of hearing loss may become important steps in supporting brain health.
Could addressing hearing loss earlier in life help support better cognitive health as we age?
MBH/PS