Here’s a link to a news story about the relationship between hearing loss and the development of dementia. In an 18-year study involving 639 subjects, Dr. Frank R. Lin and associates found that there was a correlation between hearing loss and dementia.
As this article explains, that doesn’t mean that we know there is a causal relationship. Hearing loss and dementia, could, for example, be caused by something which damages brain structures controlling memory and hearing. However, given the important roll of language in the intellectual development of children and the recent discoveries that suggest that the brain has some of the same use-it-or-lose-it properties that our muscles have, it seems reasonable to ask the question: does losing the ability to regularly use language (because of hearing loss) make us more susceptible to hearing loss?
As with most science, more research is needed. 🙂