Placebo boosts brain activity in Parkinson's patients

Date: Nov-26-2014 In a clear example of how psychology and medicine interact, a new study of

Parkinson's disease shows the powerful effect of expectation on the brain. In the

study, participants' learning-related brain activity responded as well to a placebo

as it did to real medication.

Expectation of treatment can boost the brain as strongly as dopamine drug in Parkinson's - a disease that gradually diminishes ability to get on with normal daily life.

Researchers from the University of Colorado at Boulder (CU-Boulder) and Columbia

University, New York, NY, report their findings in the journal Nature

Neuroscience.

Previous studies have suggested that the brain systems affected by Parkinson's

disease can respond to patients' expectations about treatment.

The new study explains how the placebo effect - where people believe they have

received the active drug - works by activating dopamine-rich areas in the brain of

people with Parkinson's disease.

Study co-author Tor Wager, an associate professor of psychology and neuroscience

at CU-Boulder, says the study "highlights important links between psychology and

medicine."

Parkinson's disease is a motor disorder that occurs when the brain loses cells

that produce dopamine - a brain chemical that helps control reward and pleasure

and also regulates movement and emotional responses.

The disease has four main symptoms: trembling in the hands, limbs, jaw and face;

stiffness of the trunk and limbs; slowness of movement; and problems with balance and

coordination. The symptoms of Parkinson's disease, which rarely strike before the age

of 50, gradually worsen to the point where doing normal everyday things like,

walking, talking, eating and taking care of oneself becomes very difficult.

People with Parkinson's disease struggle with 'reward learning'

Research shows that people with Parkinson's struggle with "reward learning," and

find it difficult to make motivated decisions to seek positive outcomes. Reward

learning depends on brain cells that secrete dopamine in response to rewarded actions

- such as when pressing buttons leads to receiving money.

In Parkinson's disease, patients are given the dopamine-boosting drug L-dopa to

compensate for the loss of dopamine-producing brain cells.

In their study, Prof. Wager and colleagues invited 18 Parkinson's patients to play

a computer game while they took functional magnetic resonance imaging (fMRI) scans of their

brains.

The computer game measured reward learning by getting the participants - through

trial and error - to discover which of two symbols was more likely to result in a

better outcome. There were two types of outcome: a small reward of money or avoiding

the loss of money.

As the researchers took scans of their brains, the participants played the game

three times. One time was with neither placebo nor medication, another time they took

orange juice containing medication, and they also played the game when they took

orange juice containing placebo.

On the times when they played the game and took the orange juice, the patients did

not know whether it contained the real medication or a placebo.

When they compared the game results with the brain scan data, the researchers

found the the striatum and the ventromedial prefrontal cortex - dopamine-rich areas

of the brain associated with reward learning - were just as active when the

participants played the game under the influence of the placebo as when they were

under the influence of the active drug.

Study demonstrates link between brain dopamine, expectation and learning

Prof. Wager says the results show there is a link between brain dopamine,

expectation and learning and:

"Recognizing that expectation and positive emotions matter has the potential to

improve the quality of life for Parkinson's patients, and may also offer clues to how

placebos may be effective in treating other types of diseases."

Funds for the study came from the Michael J. Fox Foundation for Parkinson's

Research.

Estimates suggest there are 6.3

million people worldwide of all races and cultures with Parkinson's disease, which tends to affect men slightly more than women.

Medical News Today recently reported a new study that followed

thousands of people for 12 years and found medium daily exercise is linked to a lower risk of

Parkinson's disease.

Written by Catharine Paddock PhD

Not to be reproduced without permission.

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Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.