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.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
No comments:
Post a Comment