The placebo effect is an interesting phenomenon in which an inactive substance can sometimes make us feel better simply because we expect that it will.
This effect can cause problems in clinical trials as a drug could be seen to be effective just as a result of this phenomenon. Therefore often trials are ‘placebo-controlled’ whereby some participants receive a placebo and others will receive the real treatment. Performing trials in this way allows researchers to understand if people who have received the real treatment have done better than what would be expected just from the placebo effect.
Why do we need a placebo group in each trial?
Every clinical trial is slightly different- involving different people, using different methods and looking at different outcomes to see if a drug or treatment is successful. Therefore the results for the placebo group will be specific to each trial and this would be hard to estimate. This is why a placebo group is needed for each clinical trial.
Also, drugs need to go through approval from regulatory agencies such as the MHRA and the EMA before they are made available to patients. These agencies look at clinical trial data to decide if a drug or treatment is both safe and effective for patients and they require placebo-controlled trials to make this decision. Therefore even if not having a placebo group could speed up a trial – it is less likely the drug would eventually be accepted by these agencies.
It is correct that other factors such as the way a medicine looks are thought to contribute to the placebo effect. In some clinical trials, including the GDNF trial, participants in the placebo group also receive the treatment after an initial period. This allows researchers to look at both the effect of the placebo and the treatment in the same participant.
We agree that clinical trials can work better and that is why we are working with drug companies, researchers and regulators as part of our Critical Path for Parkinson’s.
The Research Team