Hearing helps a child develop her speech and language skills. Hence, the importance of newborn hearing screens, which has become universal in hospitals all over the world. Children with hearing loss are being identified and treated at much younger ages than in the past. Treating hearing loss before a baby reaches six months of age results in significantly better speech and language outcomes than treating later.
Older people with hearing loss are more likely to develop Alzheimer’s disease and dementia, and hearing loss can be associated with a faster rate of cognitive decline. How might hearing loss contribute to cognitive problems and dementia? Four possible explanations have been proposed.
Four possible reasons how hearing loss contributes to cognitive problems
The most obvious is a common physiological pathway that contributes to both hearing loss and cognitive decline. From the statistical analysis, such a pattern is deemed not likely in the majority of cases.
Another possibility has to do with what researchers refer to as "cognitive load" — essentially, that the effort of constantly straining to understand stresses the brain. This one makes intuitive sense. With untreated hearing loss, the brain gets overworked by constantly straining to understand speech and sound. An overworked brain does not work efficiently. When hearing loss occurs, the brain has to overcompensate for this lost sense in some way. By placing additional emphasis on other senses like touch and vision, this process leads to fatigue and adversely affects concentration.
A third factor is that hearing loss may affect brain structure in a way that contributes to cognitive problems. Older adults with hearing loss have less gray matter in the part of their brain that receives and processes sounds from the ears. Certain structures of brain cells can shrink when they do not receive sufficient stimulation. An important research question is whether getting clearer speech signals to the brain through use of a modern hearing aid might allow these brain structures to recover their previous size and function.
Finally, social isolation plays a part. Being hard of hearing tends to isolate people from others. For someone who struggles to converse, he is less likely to want to socialize with others or even venture out of the house. Social isolation is a risk factor for cognitive decline and dementia. This is understandable as the more isolated a person becomes, the fewer stimuli his brain receives.
It is important that hearing loss receives the attention that it deserves. Effective use of hearing aids may be useful in halting the development of cognitive decline and dementia.
