Long after actual memories vanish, the emotions they leave behind may still persist, a new study has found.
In the study, neuroscientist Justin Feinstein at the University of Iowa in Iowa City and colleagues found that people with impaired memory felt sad even when they had forgotten what made them sad in the first place.
According to the researchers, the finding suggests that emotions and memory are not as connected as previously thought.
During the study, Feinstein showed a compilation of clips from heart-rending films, including Forrest Gump, to five people unable to form new memories because of damage to their hippocampus.
Ten minutes later, his team tested the memories of these patients and a group of five people with normal brain function.
The amnesiacs felt a lingering sadness even though they struggled to remember the simplest details of the clips, whereas those with healthy memories felt fine by then.
"I am surprised that the emotion lasted so long in amnesiacs," New Scientist quoted Feinstein as saying.
According to Todd Sacktor at Downstate Medical Center in New York City, the explanation may be that it is the ability to store and reflect on emotional events that will "relieve some or most of the sad feelings."
Feinstein's team also showed the two groups a series of funny clips and found a similar pattern of responses, though the difference between the two groups was less marked.
"Sadness lasts longer," he said.
The study has been published in the Journal Proceedings of the National Academy of Sciences.