It's not that depressed people can't feel good, it's that they can't hang on to that feeling, a new study claims.
The novel notion upends previous beliefs that depressed people don't even start out with positive emotions, and that they have no or little response in the areas of the brain related to good feelings.
"This tells us that a consideration of positive emotion is as important, if not more important, in understanding depression," said Richard Davidson, senior author of a study appearing online Dec. 21 in the Proceedings of the National Academy of Sciences.
"It further suggests that we may be able to develop cognitive strategies that aren't so much focused on minimizing negative emotion but rather enhancing and sustaining positive emotion," continued Davidson, who is director of the Waisman Laboratory for Brain Imaging and Behavior at the University of Wisconsin-Madison.
"Previous knowledge agreed that patients who have anhedonia [inability to experience pleasure, a component of depression] have a decreased ability to experience positive emotions," added Eva E. Redei, the David Lawrence Stein professor of psychiatry at the Feinberg School of Medicine at Northwestern University in Chicago. "The novelty of this finding is that it's not that they cannot experience positive emotions, but that they can't hang on to it."
The findings may also affect which medications are used for different cases of depression, namely that medications that affect the dopamine or reward system of the brain may be effective in this type of disorder.
"Although depression is considered a mood disorder, we really don't know how mood is disordered in depression," said Davidson.
"One of the ignored areas in depression is the possibility that one of the major abnormalities in depression is not so much a disorder of negative emotion but rather a disorder of positive emotion. The idea here is that patients with depression or at least a subgroup of them have a problem in sustaining or maintaining positive emotion."
How the study was done
The study was designed to investigate whether people with depression have trouble maintaining positive emotions over time.
Twenty-seven depressed adults and 19 non-depressed controls were asked to look at images meant to elicit positive or negative emotions, such as a nature scene or a mother hugging her baby for the positive side.
"We asked people to feel whatever emotion was elicited by the picture and then enhance the emotion to the best of their ability using mental or cognitive strategies," Davidson explained.
As an example, participants viewing the mother and baby picture could imagine the love the mother was conveying to her baby.
Participants were then asked to sustain the positive emotion for 45 minutes while undergoing functional MRI.
"What we found is that normal controls are able to do this and show activation in areas of brain that we know are important for positive emotion, especially the nucleus accumbens, which is critical for reward and positive emotion," Davidson said. "The depressed patients showed activation in this area comparable to healthy controls in the beginning but were unable to sustain this activation over time."
The research was funded by the National Institute of Mental Health, Wyeth-Ayerst Pharmaceuticals and different foundations. – (Amanda Gardner, HealthDay News, December 2009)
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