A nursing home resident with Alzheimer’s might forget receiving poor or negligent care, but the bad feelings created by ill treatment still could persist, University of Iowa researchers say.

Investigators showed sad and happy films to 17 Alzheimer’s patients and 17 people with healthy cognition, then assessed their memories of the movies and their emotional states. Those with Alzheimer’s quickly struggled to recall details of the films, or even that they had just seen a film. However, the feelings of sadness or happiness created by the movies lasted for up to half an hour.

“Quite strikingly, the less the patients remembered about the films, the longer their sadness lasted,” the university noted in a press release. “While sadness tended to last a little longer than happiness, both emotions far outlasted the memory of the films.”

The findings show that caregivers can have a powerful impact on residents’ well-being by doing “simple” things, said lead author Edmarie Guzman-Velez, a doctoral student in clinical psychology. These things might include serving favorite foods, interacting socially or joking with patients.

Full findings appear in Cognitive and Behavioral Neurology.