Thanks to many studies lead over the last years, the link between dementia/cognition and hearing loss is becoming more and more clear. What particularly links hearing loss and dementia is ageing: in fact, in many cases, they occur together getting older. There is a strong evidence that the development of dementia is higher proportionally with the hearing impairment level - mild hearing loss doubles the risk of dementia, while severe hearing loss increase the risk five times. It happens that hearing loss can be misdiagnosed as dementia or make the symptoms of dementia appear worse.
People with dementia can have difficulty communicating with others, finding the right words or signs to say something becomes quite impossible. The difficulty also stays in processing and understanding what they hear, especially if there are distractions. This difficulty in processing information (when there is competing information, auditory or otherwise), as some studies confirm, can be one of the first signs of cognitive impairment. Thinking at this, it's easy to relate the symptoms of both impairments, since they led to a similar isolation from society and to a communication refusal:
Symptoms of dementia:
Symptoms of hearing loss:
It seems that dementia appears as hearing declines. Even if the causes generating the two conditions are not 100% connected, brain abnormalities may contribute independently to both conditions. It's also possible that hearing problems can help bring on dementia, due to the impact hearing has on the brain. Hearing loss may in fact lead to social isolation (which itself has been linked to dementia) or it may interfere with the brain's division of labour.