In most cases, the person does not know that the treatment they’re receiving is actually a placebo. Instead, they believe they’ve received the real treatment. The placebo is designed to seem exactly like the real treatment, yet the substance has no actual effect on the condition it purports to treat. The placebo effect is much more than just positive thinking, however. When this occurs, many people have no idea they are responding to what is essentially a sugar pill. Placebos are often used in medical research to help doctors and scientists discover and understand the physiological and psychological effects of new medications. Here’s why the placebo effect is important, how it happens, and why it works.
Causes of the Placebo Effect
Although researchers know that the placebo effect is real, they do not yet fully understand how and why it occurs. Various factors might contribute to this phenomenon.
Hormonal Response
One possible explanation is that taking the placebo triggers a release of endorphins. Endorphins have a structure similar to that of morphine and other opiate painkillers and act as the brain’s own natural painkillers. Researchers have demonstrated the placebo effect in action using brain scans, showing that areas with many opiate receptors were activated in both the placebo and treatment groups. Naloxone is an opioid antagonist that blocks both natural endorphins and opioid drugs. After people received naloxone, placebo pain relief was reduced.
Conditioning
Other possible explanations include classical conditioning, or when you form an association between two stimuli resulting in a learned response. In some cases, a placebo can be paired with an actual treatment until it evokes the desired effect. For example, if you’re regularly given the same arthritis pill to relieve stiff, sore joints, you may begin to associate that pill with pain relief. If you’re given a placebo that looks similar to your arthritis pill, you may still believe it provides pain relief because you’ve been conditioned to do so.
Expectation
Expectations, or what we believe we will experience, have been found to play a significant role in the placebo effect. People who are highly motivated and expect the treatment to work may be more likely to experience a placebo effect. A prescribing physician’s enthusiasm for treatment can even impact how a patient responds. If a doctor seems very positive that a treatment will have a desirable effect, a patient may be more likely to see benefits from taking the drug. This demonstrates that the placebo effect can even take place when a patient is taking real medications to treat an illness. Verbal, behavioral, and social cues can contribute to a person’s expectations of whether the medication will have an effect.
Behavioral: The act of taking a pill or receiving an injection to improve your conditionSocial: Reassuring body language, eye contact, and speech from a doctor or nurseVerbal: Listing to a health care provider talk positively about treatment
Genetics
Genes may also influence how people respond to placebo treatments. Some people are genetically predisposed to respond more to placebos. One study found that people with a gene variant that codes for higher levels of the brain chemical dopamine are more prone to the placebo effect than those with the low-dopamine version. People with the high-dopamine version of this gene also tend to have higher levels of pain perception and reward-seeking.
The Nocebo Effect
Conversely, individuals can experience more symptoms or side effects as a response to a placebo, a response that is sometimes referred to as the “nocebo effect.” For example, a patient might report having headaches, nausea, or dizziness in response to a placebo.
Examples
The placebo effect can be used in a variety of ways, including in medical research and psychology research to learn more about the physiological and psychological effects of new medications.
In Medical Research
In medical research, some people in a study may be given a placebo, while others get the new treatment being tested. The purpose of doing this is to determine the effectiveness of the new treatment. If participants taking the actual drug demonstrate a significant improvement over those taking the placebo, the study can help support the claim for the drug’s effectiveness. When testing new medications or therapies, scientists want to know if the new treatment works and if it’s better than what’s already available. Through their research, they learn the sort of side effects the new treatment might produce, which patients may benefit the most, and if the potential benefits outweigh the risks. By comparing the effects of a treatment to a placebo, researchers hope to be able to determine if the effects of the medicine are due to the treatment itself or caused by some other variable.
In Psychology Experiments
In a psychology experiment, a placebo is an inert treatment or substance that has no known effects. Researchers might utilize a placebo control group, which is a group of participants who are exposed to the placebo or fake independent variable. The impact of this placebo treatment is then compared to the results of the experimental group. Even though placebos contain no real treatment, researchers have found they can have a variety of both physical and psychological effects. Participants in placebo groups have displayed changes in heart rate, blood pressure, anxiety levels, pain perception, fatigue, and even brain activity. These effects point to the brain’s role in health and well-being.
Benefits of Using a Placebo
The major advantage of using a placebo when evaluating a new drug is that it weakens or eliminates the effect that expectations can have on the outcome. If researchers expect a certain result, they may unknowingly give clues to participants about how they should behave. This can affect the results of the study. To minimize this, researchers sometimes conduct what is known as a double-blind study. In this type of study, neither the study participants nor the researchers know who is getting the placebo and who is getting the real treatment. By minimizing the risk of these subtle biases influencing the study, researchers are better able to look at the effects of the drug and the placebo. For example, imagine that a participant has volunteered for a study to determine the effectiveness of a new headache drug. After taking the drug, she finds that her headache quickly dissipates, and she feels much better. However, she later learns that she was in the placebo group and that the drug she was given was just a sugar pill.
Placebo Effect Outcomes
While placebos can affect how a person feels, studies suggest that they do not have a significant impact on underlying illnesses. A major review of more than 150 clinical trials involving placebos found that placebos had no major clinical effects on illnesses. Instead, the placebo effect had a small influence on patient-reported outcomes, particularly of perceptions of nausea and pain. However, another review conducted nearly 10 years later found that in similar populations, both placebos and treatments had similar effects. The authors concluded that placebos, when used appropriately, could potentially benefit patients as part of a therapeutic plan.
Depression: The placebo effect has been found to impact people with major depression disorder. In one study, participants who weren’t currently taking any other medication were given placebo pills labeled as either fast-acting antidepressants or placebo for one week. After the week, the researchers took PET scans and told the participants they were receiving an injection to improve mood. Participants who took the placebo labeled as an antidepressant as well as the injection reported decreased depression symptoms and increased brain activity in areas of the brain linked to emotion and stress regulation.Pain management: A small 2014 study tested the placebo effect on 66 people with episodic migraine, who were asked to take an assigned pill—either a placebo or Maxalt (rizatriptan), which is a known migraine medication—and rate their pain intensity. Some people were told the pill was a placebo, some were told it was Maxalt, and others were told it could be either. Researchers found that the expectations set by the pill labeling influenced the participants responses. Even when Maxalt was labeled as a placebo, participants gave it the same rating as a placebo that was labeled Maxalt.Symptom relief: The placebo effect has also been studied on cancer survivors who experience cancer-related fatigue. Participants received three weeks of treatment, either their regular treatment or a pill labeled as a placebo. The study found that the placebo (despite being labeled as such) was reported to improve symptoms while taking the medication and three weeks after discontinuation.
A Word From Verywell
The placebo effect can have a powerful influence on how people feel, but it is important to remember that they are not a cure for an underlying condition. Healthcare providers aren’t allowed to use placebos in actual practice without informing patients (this would be considered unethical care), which reduces or eliminates the desired placebo effect. However, by using placebos in research, during which they don’t have to inform the participant, scientists are able to get a better idea of how treatments impact patients and whether new medications and treatment approaches are safe and effective.
