Central auditory processing dysfunction is the inability to pick out sounds among other noise - such as conversation at a party - even though one's hearing is normal in other circumstances. Researchers at the University of Washington, Seattle, studied 313 people, with an average age of 80, who had been participating in a dementia surveillance programme since 1994. 17 had dementia, 64 had mild memory impairment and 232 had no memory problems. Participants completed three tests designed to measure central auditory processing; one in which nonsense sentences were read out over the top of an interesting narrative and two involving different numbers and sentences being read into each ear simultaneously. The average scores were significantly lower in the people with dementia and mild memory impairment even when age and hearing status were allowed for.
You can find out more about this research at