The scientists still have not found out why untreated hearing loss increases the risk of dementia and cognitive decline.
Reduced audiological input
Some researchers suggest that the reduced audiological input to the brain may contribute to cognitive decline and dementia. The reason should be that brain activity is reduced by the reduced audiological input and that the brain is like a muscle that needs to be used and trained to keep on working well.
Others that have investigated the relationship between hearing loss and dementia suggest that a common pathology may cause both conditions or that the strain of decoding sounds over the years may overwhelm the brains of people with hearing loss, leaving them more vulnerable to dementia.
The investigators also suggest that hearing loss requires so much ”brain effort” over the years to decode sounds into useful information, that those with hearing loss become more vulnerable to dementia.
Another theory is that hearing loss could lead to dementia by making individuals more socially isolated, a known risk factor for dementia and other cognitive disorders.
Source: ”Hearing well to train your brain” by Prof. Frank R. Lin and Prof. Sophia E. Kramer