Washington, Dec 22 (IANS) Depression can zap the brain’s ability to sustain positive emotions, according to a new study.
It also affects the reward circuitry of the patients, the study says.

The findings challenge previous notions that the depressed show less brain activity in areas associated with positive emotions. Instead, it suggests similar initial levels of activity, but the inability to sustain them over time.

“Anhedonia, the inability to experience pleasure in things normally rewarding, is a cardinal symptom of depression,” explains University of Wisconsin-Madison (UW-M) graduate student Aaron Heller, who led the project.

“Scientists have generally thought that anhedonia is associated with a general reduction of activity in brain areas thought to be important for positive emotion and reward,” Heller adds.

“In fact, we found that depressed patients showed normal levels of activity early on in the experiment. However, towards the end, those levels of activity dropped off precipitously,” he says.

“Those depressed subjects who were better able to sustain activity in brain regions related to positive emotion and reward also reported higher levels of such emotion in their everyday experience,” Heller continues.

“Being able to sustain and even enhance one’s own positive emotional experience is a critical component of health and well-being,” notes senior study author, Richard Davidson, UW-M professor of psychology and psychiatry.

These findings are based on a study of 27 depressed patients and 19 control participants. Heller and colleagues used functional magnetic resonance imaging (FMRI) to measure brain activity in the target areas.

The scientists examined the extent to which activation in the brain’s reward centres to positive pictures was sustained over time, says a UW-M release.

The new work was reported online this week in the Proceedings of the National Academy of Sciences.