Placebos ease unpleasant emotions, brain scans show

Placebos ease unpleasant emotions, brain scans show

Last Updated Wed, 15 Jun 2005 16:33:54 EDT
CBC News

Placebos can bring pain relief but they can also reduce anxiety by affecting the same brain circuits, researchers say.

Swedish scientists hypothesized that placebos could reduce emotional perception the same way the blank medicines relieve pain.


Placebos may help relieve both pain and impact of unpleasant emotions.
To explore the idea, Predrag Petrovic of the Karolinska Institute in Stockholm tested the effect of a placebo on how volunteers rate unpleasant pictures such as mutilated bodies, compared to neutral pictures.

Researchers gave 15 female volunteers real anti-anxiety drugs, after telling them the drug would reduce their unpleasant perceptions of the photos.

Scientists know that in placebo tests on pain, the expectation of relief is important.
Then the volunteers were given an antidote to the anti-anxiety drug. They were told the unpleasant perceptions would be restored.

The next day, investigators repeated the experiment. But instead of giving the anti-anxiety drugs, they used a saline solution as a placebo.


Expectation of relief

As the volunteers looked at the pictures, their brains were scanned using functional magnetic resonance imaging, which tracks blood flow as a measure of brain activity.

The placebo reduced ratings of unpleasant pictures by about 29 per cent, as the scans showed less activity in the brains' emotional centres, the team reported in the June 16 issue of the journal Neuron.

"In conclusion, this study demonstrates that very similar mechanisms are involved in the placebo response of emotional stimuli and in placebo analgesia," the team wrote.

Based on their results, the study's authors propose generalizing the concept of a placebo effect to emotional processing, noting both are influenced by subjects' expectations.

Source[/color]