Expectation May Affect Placebo Response in Parkinson's Patients

According to recent study done in Canada, patientschance of getting the drug showed significantly higher
suffering from Parkinson's disease show enhancedamounts of dopamine, which is a neurotransmitter. This
brain chemical reaction just because they have aneffect was not observed in any of the other patients.
expectation of getting a helpful drug even though theyThe strange part of the study is that the release of
have been given a placebo instead.more amount of dopamine was only seen when the
The study was conducted on 35 people sufferingparticipants were informed that they had three in four
from either mild or moderate Parkinson's disease.chance of receiving the drug and not when they were
These patients were being treated with the help of ainformed that they had a hundred percent surety of
drug called levodopa. At the start of the study, thereceiving the drug.
patients had to undergo PET scans of the brain. ThenHowever, researchers claim that the result is what
they were given the drug and were subjected tothey expected and in line with dopaminergic activation,
another scan.which occurs when a person expects a reward but is
On the 2nd day of the study, the participants werenot certain of getting it. Basically what this means is
informed separately that they had a 25, 50, 75 or 100that when a patient is certain that he or she is going to
percent chance of getting the drug before they had aget the drug, the dopamine reward response is not
brain scan. However, none of the participants wereseen.
given the drug. Instead they were all given a placebo.The reason this new study is important as clinical trials
On checking the participants, it was found that thosecan be designed taking into consideration the dopamine
who were informed that they had a 75 percentreward response.