A research team at Chung-Ang University Hospital has found the mechanism between hearing loss and Alzheimer's disease, the hospital said Monday.
|Professor Chang Mun-young|
Until now, several epidemiological studies have suggested a correlation between hearing loss and Alzheimer's dementia. However, they lacked the scientific basis that explains the mechanism underlying the causation of hearing loss and Alzheimer's dementia.
To secure the scientific basis, Professor Chang Mun-young at the hospital studied the effects of hearing loss on cognitive function reduction by using a hearing loss animal model.
The professor's team administered amyloid-β, a causative agent of Alzheimer's disease, to two groups – normal and deaf mice. During the trial, the team only administered small amounts amyloid-β, as their goal was to identify the risk factors of Alzheimer's disease and not cause severe brain damage.
Afterward, Professor Chang divided the subjects into four groups -- healthy hearing group, amyloid-β injected normal hearing, deaf group, amyloid-β injected deaf group – and performed a brain area-specific cognitive function test.
As a result, the cognitive function of the hippocampus was significantly reduced by 30 to 85 percent in the amyloid-β injected deaf group, while the cognitive function did not decrease in the other three groups. Also, the hippocampus synapse level of the amyloid-β injected deaf group reduced by 30 to 40 percent compared with the other groups.
"Unlike dementia risk factors such as age, family history, hearing loss can be controlled through hearing aids or cochlear implant," Professor Chang said. "Such procedures can help slow and prevent the progression of Alzheimer's disease."
Acknowledging that hearing loss is a risk factor for dementia and conducting hearing rehabilitation will contribute to the prevention of dementia, he added.
The journal Behavioural Brain Research published the results of the study.
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