The placebo effect is an outcome resulting from a person’s anticipation that an intervention will lead to a result, the outcomes of which can be either positive or negative. Although the placebo effect has been known for a long time, it is still not understood what actually causes it. With that being said, we can all agree that using the placebo effect can be a powerful tool to help improve health.
Examples of the Placebo Effect
Study 1 – Use of “Antihistamine” Cream on a Rash. Participants in the study had an irritant rubbed on their forearm which produced a small rash. The participants were then divided into 2 groups. In both groups a medical professional applied the same placebo cream with no active ingredients. One group was told that an antihistamine cream was being applied (to reduce inflammation), the other was told that a histamine was being applied (to increase inflammation). The group that believed they were being given a treatment to reduce the rash saw a significant decrease in the size of the rash while the group that believed they were being given an inflammatory cream saw an increase in the size of the rash. The subject’s belief about the treatment actually led them to have the health outcome they thought they would have, regardless of the efficacy of the treatment itself.
Positive Physiological Effects
Study 2 – Effects on Ghrelin. Participants consumed identical 380-calorie milk shakes. On one occasion, the label said it contained 140 calories (Weight Loss Shake), and on another, the label said it contained 620 calories (Meal Replacement Shake). The “meal replacement” condition produced a steeper decline in ghrelin (a satiety hormone) and greater self-reported satiety compared to the “weight loss” condition. People who believed that they were consuming a nutrient dense shake compared to a weight loss shake actually had a better hormonal response than those who believed they were restricting themselves.
Negative Behavioural Effects
Study 3 – Effects on Food Consumption. All participants received a placebo pill and were then randomized to conditions in which they were told that they had taken either a placebo or weight loss pill. Those who were told that they had taken a weight loss pill ate more during a taste test and preferred larger quantities of sugary drinks compared to those who were told that they had taken a placebo. The findings suggest that those who believed that they took the weight loss pill may have perceived that the medication gave them greater leeway with regard to intake when offered food during the taste test.
The Power of Social Context
Study 1 Revisited – Researchers went back and changed a few variables in the antihistamine study. This time, all participants were told that an antihistamine was being applied to the rash. What the researchers did this time was split the participants into two groups and change the persona of the doctor. One groups medical professional greeted the participants warmly, wore a badge that said senior doctor, showed interest and empathy and carried out the test with an obvious level of confidence. In the second group the Doctor deliberately avoided eye contact, was short with the patients, wore a badge saying ‘trainee’ and fumbled while putting on the blood pressure cuff. In this instance the group that felt they were in safe, competent hands saw an even greater reduction of inflammation than participants in the first study while the group treated by the seemingly cold, incompetent doctor saw a significantly less decrease in the size of their rash. Some even saw a slight increase!
The placebo effect, although not fully understood, can be a powerful tool when it comes to managing health. Its effect can be used to both positively and negatively affect health outcomes. Furthermore, the social context in which the placebo effect is used will magnify the effects to a significant degree.