People with dementia remember the feelings associated with an event for a longer time, a study says, feeling the emotion after the memory has vanished.

Although people with Alzheimer's disease forget things quickly, they can remember the feelings associated with an event for a longer time, a US study has found.

Alzheimer's patients and healthy people were shown 20-minute film sequences which were either happy or sad for a study carried out by the University of Iowa. Five minutes later the study participants were questioned about what they could remember of the films.

As might be expected, the Alzheimer's sufferers remembered significantly less of the film content than did the healthy participants. Some didn't even remember that they had seen a film.

However, the feelings of sadness or happiness that had been aroused by the films remained for up to half an hour after the showing. It was particularly striking that the feeling of sadness stayed with the dementia sufferers longer, the less well they were able to remember the film.

The researchers concluded with an encouraging message for relatives and loved ones of dementia sufferers: even though a sufferer might not be able to remember a visit, the positive feelings from one can still persist long after.

Copyright AAP 2014.