The power of placebo

If you have a headache and take some medicine you’ll probably feel better. But how much of that is due to the drug you’ve taken, and how much is down to your belief it will work?

What is the placebo effect?

The placebo effect is a remarkable phenomenon in which an inactive substance, such as sugar or water, can sometimes make us feel better simply because we expect it will. It’s a phenomenon that we don’t completely understand. But we can see it working in all kinds of ways, and all kinds of circumstances.

Placebos are most often given to people participating in clinical trials — studies that test the effectiveness of new treatments. In a ‘placebo-controlled’ trial, some participants will receive the real treatment and some a placebo. The participants don’t know whether they are getting the real deal or the placebo, and neither do the researchers running the study. When the study finished, all is revealed and the researchers can look to see if the people who received the real treatment have done better than those who received the placebo.

The placebo effect in Parkinson’s

The placebo effect can be surprisingly potent, and several studies have revealed the powerful effect placebos can have on people with Parkinson’s.

In 2010, Canadian researchers carried out a study to see how differing expectations of receiving the active treatment affects the strength of the placebo effect. Participants were told that they had a 20%, 50%, 75% or 100& chance of receiving levodopa, a Parkinson’s medication that increases dopamine levels in the brain. All of the participants actually received a placebo. Fascinatingly, though, only those who believed they had a 75% chance of getting levodopa experienced significant improvements.

Last year, US research showed how much we think a treatment costs can also affect the power of the placebo response. People with Parkinson’s who were given what they believed to be an expensive drug experienced more significant improvements compared to those who thought the drug they were taking was cheap.

Understanding the placebo response in Parkinson’s is of critical importance to improving the way clinical trials are designed. We need to be able to test new treatments in a way that minimised the placebo effect and help us see their true value.

“We often here of the placebo effect in Parkinson’s. Usually it is seen as a problem, because it makes it difficult to interpret the results of clinical trials. I see it differently. Placebos could be used as therapies in their own right, after all clinical trial after clinical trial has found that they work. We could even engineer them to maximise their effectiveness. And if they lose their effectiveness over time, there’s an infinite number of new placebos to move to.”
John from the Parkinson’s UK forum

Could placebos be used to treat Parkinson’s?

The use of placebos in medicine is a bit of an ethical minefield, especially where any deception is involved. It can also have serious consequences. Antibiotics have been over -prescribed to people with viral infections where antibiotics are not effective and act as no more than a placebo. This over-use has contributed to the rise of antibiotic resistance.

Surprisingly, even when you know the treatment you’re receiving is a placebo it may still make you feel better. This was reflected in a recent survey that suggested many people are open to the idea of using treatments that may boost the placebo response. However, rather than be deceived, they wish to have an open and honest discussion with their doctors about their use.

The placebo effect is powerful, but it does have limits. It cannot stop the progression of Parkinson’s or the loss of cells in the brain. It may also vary a lot from person to person, and also over time. So while it may be a useful tool for developing therapies that can ease symptoms like pain and anxiety, we know ultimately there is a need to develop treatments that tackle the underlying biology to provide the real solutions.