The Power of Perception: Placebos, Costs, and Parkinson’s Disease

Researchers use the clinical trial process to study the effects of drugs and measure how patients’ symptoms improve. One well-known phenomenon that occurs in clinical trials is the placebo effect – people get better even when taking a fake treatment, if they believe it is an effective product. The placebo effect reveals the power of the mind to produce beneficial effects. Many trials compare a new treatment against a placebo, in which one group receives the medication and the other group receives a placebo, like an injection of saline or a sugar pill. Neither group knows which is the real thing and which isn’t, so their expectations of receiving treatment are the same. Researchers then compare the results of each group to see if the medication provides more of a benefit than the placebo. Amazingly, some people notice an improvement in their symptoms even though all they have received is a placebo.

Many research studies have documented that there is a large placebo effect seen in patients with Parkinson’s disease (PD). But what effect does the cost of a medication have on a person’s expectations of its effectiveness? That’s what one study set out to investigate, with some surprising results. The researchers wanted to understand the perceived value of a drug, as measured by its cost. They conducted an experiment on 12 people with moderate to severe PD. The participants were told they were researching two injectable dopamine agonist treatments – one that was $100 a dose and another that was $1,500 a dose. After more than 12 hours from their usual levodopa medication, when the patients were in an “off” state and experiencing symptoms of PD, they were randomly selected to either receive the “cheap” drug first, or the “expensive” drug first. Each group received the second drug after the first wore off, in approximately 4 hours. The patients’ motor function was measured before and after each treatment, and they were given magnetic resonance imaging (MRI) scans to measure brain function.1

The patients didn’t know that both the “cheap” drug and the “expensive” drug were actually placebos: the injections contained only saline.

Improvement in symptoms

When the patients in the trial received the “expensive” drug first, their motor functions improved two-fold compared to the “cheap” drug, although the improvement was still less than what is seen with levodopa treatment. Even the “cheap” drug made an improvement in PD symptoms, proving the power of the individual’s expectations of treatment in their effectiveness.1

Parkinson’s, dopamine, and the placebo effect

Parkinson’s affects the brain cells that produce dopamine, and the reduction in the amount of dopamine in the brain causes the motor symptoms like tremor, slowness of movement, stiffness, and difficulty with balance. Although exactly how placebos work isn’t clear, experts know that it increases neurotransmitters like endorphins and dopamine in the brain, which likely explains the significant placebo effect seen in people with PD.1,2

While placebos have a therapeutic benefit, they do not cure you. Researchers at Harvard University that have studied the placebo effect believe that placebos work best on symptoms that are modulated by the brain, like the perception of pain, fatigue, and nausea.2

Can you use the placebo effect on yourself?

Placebos in clinical trials seem to work because people who receive them don’t know they aren’t “real” medicine. But some studies have shown that even when patients know they are getting a placebo, there’s still some benefit and reduction in symptoms (like pain). The ritual of taking medication seems to trick the body into believing there’s a benefit.

Other ways to use the placebo effect on yourself include rituals of healthy living, like eating right, getting regular exercise, and practicing self-care.2

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