What is the placebo effect?
The placebo effect in medicine is defined as a change in outcome, behavior or response to an inert treatment compared with active treatment. For example, in medication research trials, the placebo is an inactive (‘sugar pill’) pill that looks similar to the treatment pill being studied for its effect. By comparing the changes between the two groups, researchers can determine if the active pill really does have a true and unique effect.
There are many personal factors that account for the placebo effect. Research confirms that the placebo effect is affected by our cognitive thoughts or what we think about the treatment and our conditioned learning or how our prior experiences influence our response. Other factors include the quality of interaction with our doctors, supportive care, trust and empathy we receive during treatment.
The placebo can be either positive or negative. Just wishing something to work could improve the chance of success. The opposite is true if you are skeptical and have negative feelings about a treatment (a negative effect is called the nacebo effect).
How does the placebo affect research and treatment?
Because of the strong placebo effect, we must be careful in how we interpret claims for new treatments. A positive or negative effect could simply be due to placebo and not the real treatment. Research is often designed to try to control or eliminate this placebo effect. The randomized controlled research trial commonly used to study new treatments and interventions is designed with this in mind. In the randomized trial, participants are randomly divided into a group that gets the treatment under study and another that gets placebo (i.e. sugar pill, sham surgery). Ideally both research participant and researcher are not aware of which group participants are assigned. This avoids the bias in measurement that researchers can bring to the table. In this way, the placebo effect (i.e. results obtained from the group that unknowingly received inactive treatment) is compared to that seen in the active treatment group. If there is a significant difference (negative or positive) the treatment does have an effect.
What contributes to the placebo effect?
The placebo effect is associated with cell changes in brain areas involved in the control of reward and learning. Researchers believe the following factors contribute to the placebo effect:
- Prior experience with treatment. If you had a good experience with a pill or similar treatment you are more apt to experience a placebo effect with a new treatment. Each of us has our own personal experiences with healthcare and treatments - these experiences will influence our expectations for treatment. A positive experience can lead to a larger placebo effect. Alternatively a negative experience can lead to a worsening effect (called nacebo). Psychologists call this response conditioned learning.
- Expectations for treatment. If you believe a treatment will have dramatic results the placebo will be greater. This may be why studies show a greater placebo rate with a larger pill v. smaller pill, brand name v. generic medicine, invasive surgery v. medicine, pill v. injection.
- Value and importance given to treatment. A treatment that is highly valued due to a person’s hopes, ideals and belief can carry a higher placebo rate. In other words, if a treatment is expected or hoped to have a dramatic effect or change in one’s symptoms or disease, then so may the associated placebo. This is important to consider in highly anticipated research studies such as stem cell therapy or gene therapy. One’s ideals and values can change the placebo effect. For example herbs and natural supplements can have a high placebo rate due to the fact that people who take them often have a belief that they are safer and offer healthier natural healing, they same may be true for surgery or important breakthroughs such as gene therapy or stem cell therapy. A treatment that aligns with your spiritual or cultural beliefs is also more likely to yield positive results than one that does not.
What is known about the placebo effect and Parkinson’s?
The placebo effect is significant in Parkinson’s studies. The placebo is real and can mimic the actual biochemical and physiologic changes of real treatment. In one study, Parkinson’s patients were given a placebo (saline) injection to treat Parkinson’s motor symptoms (de la Fuente-Fernandez, Science 2001). People that improved with saline (placebo response) had a significant increase in brain dopamine release. The authors believe that dopamine release “is linked to the expectation of a reward, in this case, the anticipated therapeutic benefit”.
A placebo effect is measured in all studies of medicine. Even surgery carries a placebo effect. A study of fetal cell transplant and a gene therapy study (called Ceregene) showed that transplant improved symptoms but as a whole outcomes were not better than sham surgery (fake surgery in which patients thought they received the transplant). Another study of patients with DBS showed that people did better after programming if they were coached that results would be positive by their programmer and did worse if they were given negative expectations.
The placebo effect may be particularly strong in Parkinson’s due to the role of dopamine in our brains reward system and the role of key frontal brain regions that receive projections from the basal ganglia and are involved in thought patterns known to influence the placebo response.
How does the placebo affect me?
The placebo effect is real. It is neither good nor bad. It is important to be aware of this effect when exploring treatments. The accompanying article, Find your Sugar Pill, explores the ways you can benefit from the placebo and harness our mind’s power to influence therapy.
Are benefits true or placebo?
It is important to know if a treatment outcome is due to the treatment itself, entirely due to placebo. Medical research uses the randomized controlled trial to answer this question about a given therapy. In the randomized trial, participants are separated randomly to a group that gets the treatment and another that gets placebo (i.e. sugar pill, sham surgery). Ideally both research participant and researcher are not aware of treatment for any given person. In this way, the placebo effect (i.e. results obtained from the group that unknowingly received inactive treatment) is compared to that seen in the active treatment group. If there is a significant difference (negative or positive) the treatment does have an effect.
When possible, consider treatments that have been studied in a randomized placebo controlled fashion over treatments that treatments that have only been researched using open label studies (no placebo given and the entire group gets active treatment). The same is true for treatments that use only testimonials of individuals or groups as evidence of benefit. This is especially important for medications.
However, not all treatments can or have been studied using the randomized placebo controlled trial. Just because a treatment has not been studied in this fashion does not mean it is ineffective. Some treatments just cannot be studied in this way. Many alternative therapies fall into this category. For instance, it is difficult to find a placebo for treatments such as massage or acupuncture. That does not mean these treatments are not beneficial.
One must be careful, however, in choosing treatments. Parkinson’s can lead to daily frustrations and a sense of desperation for some people to ‘try anything’. Coupled with this, is the power of persuasion and strong marketing techniques accessible to everyone on the internet. The following recommendations will help you find a treatment appropriate for you:
- If the treatment you are interested in is not yet proven effective, consider enrolling in a controlled research trial if one is available. This helps insure safety, contributes to scientific knowledge, identifies new treatments and helps advance care for all in the Parkinson’s community. See accompanying article; Are clinical research trials right for me? Talk to your healthcare provider about all treatments you are considering rather than ‘going it alone’.
- Seek similar alternative treatments that are proven in place of one not yet proven. An example may be the use of Yoga shown to be effective for medical conditions versus a new exercise fad.
- Consider the risk v. benefit to you when selecting a treatment. If a treatment carries higher risk than it should meet the requirement for a greater level of proof as to benefit than a treatment with lower risk. For instance, if you feel good after a massage and this treatment carries little risk to you (other than cost) than you may not need a higher level of proof of its direct effect.
Learn more about the powerful role your mind plays in health and wellness in the Mind Power series: