http://www.medpagetoday.com/Geriatrics/Dementia/36946
This study shows a link between hearing loss and mental decline - hardly a surprise. What I would like to see is a study comparing deafies who continue to battle with hearing loss (seek and persist with hearing aids and other forms of assistance) as against those (probably a majority) who, simply, withdraw. I would expect battlers to show slower loss of cognitive ability than those who drift into a silent world.
Figures in the report about progressive decline in hearing/sight with age are interesting.