The placebo effect is when a person has a response to a fake intervention, such as when someone is given a sugar pill and they report that it helped with their headaches.
This effect is often discussed in the context of medical research. Although the patient is given a substance which contains no active medical ingredients, it still affects symptoms. And those effects are not just imagined or “all in the mind.”
A person’s actual medical symptoms may improve, even though the medication they took was nothing more than a sugar pill.
The placebo effect poses a challenge for medical research. If people that do not receive the medical treatment improve, then it can be difficult to distinguish the real benefits of the medical treatment over the benefits of the placebo.
To make matters more complicated, it is also possible that both the placebo and the medical intervention have positive effects, which may be additive or interactive.
Placebo Effect Examples
- Pain Relief: The placebo effect is perhaps best demonstrated with pain relief. In numerous studies, patients given a sugar pill or saline injection, but told they are receiving a potent painkiller, often report substantial reduction in pain. This is believed to be because their expectation of relief causes their brain to release endorphins, natural painkillers.
- In Cancer-Related Fatigue: This study supplied cancer patients with OLPs, so they knew they were taking placebos. Control group patients received no placebos or any kind of treatment. “The OLP group reported significantly improved CRF…while the control group did not.”
- Depression: In studies on depression, placebos can have a very significant effect. Participants who believe they are receiving a new, potent antidepressant often report improved mood and energy levels, despite only receiving a sugar pill. For example, this study involved patients with major depression being given open-label placebos described as “active” or “inactive.” Patients in the “active” placebo condition showed a decrease in depressive symptoms compared to patients in the “inactive” placebo condition. Based on PET scans, these results were related to increased opioid neurotransmitter released in regions of the brain “associated with better antidepressant treatment.”
- Parkinson’s Disease: Patients with Parkinson’s disease have been found to have improved motor function after receiving a placebo treatment. This is thought to be because the expectation of improvement triggers the release of dopamine, a neurotransmitter that is deficient in people with Parkinson’s.
- Irritable Bowel Syndrome (IBS): In a study, IBS patients were given a placebo but were told that it was a powerful drug that could significantly reduce their symptoms. A significant number of these patients reported feeling better and having less severe symptoms after taking the placebo.
- Migraines: In trials of migraine medications, it’s been observed that patients who receive a placebo often report a decrease in the severity and frequency of their headaches. This may be due to an expectation-based increase in the production of endorphins.
- Asthma: While placebos cannot change the physical constriction of the airways in people with asthma, patients who receive a placebo treatment often report feeling better and experiencing less shortness of breath, likely due to their expectation of improvement.
- Hypertension: In clinical trials, some patients with high blood pressure who receive a placebo experience a decrease in their blood pressure. This might be attributed to the relaxation and reduced anxiety that comes from believing they are receiving treatment.
- Sleep Disorders: In placebo-controlled trials for sleep disorders, patients are often highly susceptible to placebos both in terms of pills and doctors’ suggestive language. For example, in one study, researchers informed some participants that the quality of their sleep was either “above average” or “below average” based on amount of time spent in REM. They were then administered a test of cognitive performance that had been previously determined to be affected by sleep deprivation. The results indicated that “Assigned sleep quality but not self-reported sleep quality significantly predicted participants’ scores” on cognitive performance.
- Arthritis: Some patients with arthritis report less joint pain after taking a placebo, potentially due to the expectation of pain relief leading to a reduction in perceived pain and increase in pain tolerance.
- Placebo Surgery: In some cases, “sham” surgeries where the patient is led to believe they’ve had an operation but haven’t actually have led to similar improvements as real surgeries. In one famous study, doctors conducted knee surgery on some patients while others only received a small incision. Surprisingly, the results of a follow-up found that “the outcomes after arthroscopic partial meniscectomy were no better than those after a sham surgical procedure.”
- Open Label Placebos: An open label placebo (OLP) means that patients know they are taking a placebo. Surprisingly, the results of this study found that, compared with standard treatment, “OLP elicited greater pain reduction… with moderate to large effect sizes… Open-label placebo treatment also reduced disability.”
- Observational Learning and Placebo Effects: Research participants were administered mild electric shock under different conditions. In one condition, participants observed another person (an accomplice of the study) receiving mild shock but indicated it was not painful. Results found that although participants in this condition received the same level of shock as participants in the other conditions (which did not involve social observation), they reported less pain. Even more interesting, their perception of less pain was related to their degree of empathy.
- Acupuncture: Sham acupuncture, where needles are placed at non-acupoint locations or don’t pierce the skin at all, often produces similar improvements to pain and well-being as real acupuncture. This is believed to be due to the placebo effect.
- Heart Disease: In some trials of medications for non-life-threatening heart conditions, patients given a placebo have reported decreases in chest pain and other symptoms. This is likely due to decreased stress and anxiety, which can contribute to these symptoms.
- Eczema and Skin Disorders: Patients in trials for new dermatological treatments sometimes see improvement in their conditions with placebo creams or pills, likely due to their belief in the treatment’s efficacy reducing stress, a common trigger for outbreaks.
- Allergies: In trials of new allergy medications, patients given a placebo often report a reduction in their symptoms, possibly due to the calming effect of perceived treatment on the immune system.
- Tinnitus: Some people with tinnitus (ringing in the ears) report reduced symptoms after receiving a placebo treatment, likely due to the reduction in stress and anxiety that can exacerbate tinnitus.
- Menopause: In studies on menopause symptoms like hot flashes, placebos have often produced a significant decrease in symptom severity. This could be due to the power of expectation influencing the subjective experience of these symptoms.
- Obesity: In trials of weight-loss drugs, patients receiving a placebo sometimes report weight loss and increased feelings of fullness. This is likely due to increased motivation to monitor diet and exercise habits during the trial period.
- Chronic Fatigue Syndrome: Patients suffering from chronic fatigue syndrome sometimes report improvements in energy levels and overall well-being when given a placebo, potentially due to an increased sense of hope and reduced stress levels.
- Pill Color and Perceived Effects: Researchers in the Netherlands conducted a review of 12 studies examining the color of drugs and their perceived effectiveness. The review found that red, yellow, and orange drugs are associated with a stimulating effect while blue and green drugs are associated with a relaxing effect. Similarly, in this article, Dr. Kamerow describes his time working as an intern in a large hospital early in his career. The hospital had “special” painkillers that were for patients that abused pain medication. He explains that the pills were viewed by many patients as “must haves,” even though both pills only contained either aspirin or Tylenol.
- Creating Expectations as a Placebo Effect: Placebo effects can also be demonstrated through the power of suggestion. A commentary regarding overt versus covert treatment revealed several interesting findings. For example, administering morphine along with a statement suggesting effectiveness such as “the treatment that you are about to receive is potent in relieving your pain,” induced greater benefits than if nothing was said at all.
Placebo Effects in Experimental Research
Placebo effects are used in research where two groups are given separate treatments (one a real treatment and the other a placebo). Each individual doesn’t know what group they’re in. Researchers compare the groups, assessing whether the group that got the real treatment received greater benefits than the placebo group.
Because the placebo effect is so pervasive, and confuses interpretation of treatment effectiveness, medical research often involves at least two groups of participants.
At the beginning of the study, researchers randomly assign participants to be in either one of two conditions: the treatment group or the control group.
Random assignment is an extremely important procedure. By definition, it means that each participant has a 50/50 chance of being assigned to either one of the two conditions.
It is a carefully controlled process and done in such a way so as to ensure that the researchers do not know which participants are assigned to which group.
The participants themselves also do not know which group they are assigned to.
When neither participants nor researchers know, it is referred to as a double-blind experiment. With inclusion of random assignment, it becomes a double-blind randomized controlled trial (RCT).
Read Also: Random Assignment Types and Examples
One group will receive the real treatment (treatment group) and the other group will receive a placebo (control group).
Some studies also include a third group called the wait-list control. Participants in this group are told they are on a waiting list and will be contacted later for participation.
In reality, they are part of the study and serve as a kind of baseline to compare the effects of the other two conditions.
At the end of the study, the groups are compared. If the treatment is effective, then the targeted symptoms should be reduced. Ideally, they are reduced to a greater extent than that produced by the placebo effect in the control group.
That is a key comparison that is made in each study.
Types of Placebos
There are different types of placebos that are used in medical research. Each one can produce the placebo effect.
- Sugar pill: Because a lot of studies involve a medication delivered in pill form, the placebo is also made to look like a pill. Researchers will make sure that the size, shape, and color of the sugar pill are the same as the actual treatment pill.
- Saline injection: When the medical treatment is delivered in the form of a shot, then the participants in the control condition will also receive a shot.
- Consumable liquid: If the research involves administering the medical treatment in liquid form, then control group participants will also consume a liquid. The researchers make sure that the placebo liquid is as similar to the treatment liquid as possible, including color, taste, and amount consumed.
- Impure placebos: Some placebos contain ingredients that have a pharmacological effect, but not on the medical ailment under treatment. According to Jütte (2013), physicians in the past started the habit of administering impure placebos to satisfy the expectations of patients, to put their mind at ease.
Placebo vs. Nocebo Effects
Placebo and nocebo effects refer to the positive and negative results (respectively) that patients experience when being told they are receiving a treatment.
Even though a real treatment is not administered, patients will often display results that are consistent with an actual treatment. When these results are positive and in line with treatment expectations, this is called the placebo effect.
However, when the patient displays side-effects or other harmful effects, it is referred to as the nocebo effect. The negative expectations of the patient can cause negative consequences.
Unfortunately, in addition to side-effects being unwanted and sometimes dangerous, as many as 25% of patients receiving placebos in clinical trials discontinue participation because of side effects (Rief et al., 2006; Häuser, et al, 2012).
Origins of the Placebo Effect
Walach (2003) traces the term placebo as far back as the Middle Ages from the singing of a song on one’s deathbed. Since the singing was performed by others and not the one dying, the term became associated with a kind of “nearly fraudulent replacement of the real” (p. 178).
According to Wampold et al. (2005), the term placebo took hold in the 18th century as it was common practice for physicians to administer just about any substance to please the patient, even though it was widely recognized “that most substances given by doctors to patients were not helpful” (p. 836).
Jütte (2013) identifies the English physician Alexander Sutherland as introducing the term “placebo” into medical jargon in the 18th century.
As explained by Wampold et al. (2005), modern medicine eventually strived to establish legitimacy by demonstrating that medical treatments were effective via physiochemical processes; not just tricks of the mind.
At the very least, the goal should be to find treatments that produce benefits over and above the placebo effect.
Hence, the double-blind randomized controlled trial (RCT). An experimental design that allows doctors to compare the benefits of medical treatment with the benefits of the placebo.
After data has been collected, statistical analyses determine if that difference is meaningful and valid.
The placebo effect refers to the positive effects of a substance which contains no ingredients that are supposed to impact a medical or psychological condition.
Placebos can take many forms; sometimes being a sugar pill, ingested liquid, or simple saline injection.
However, as it turns out, many times a placebo does have a positive impact on symptoms.
This has presented medical researchers in particular with a substantial challenge. It is imperative to the profession that medical treatments have demonstrated efficacy, over and above what a placebo can provide.
In order to make that determination, researchers employ carefully designed studies that involve randomly assigning some patients to receive a medical intervention while others receive a placebo.
If the medical treatment is effective, then it should produce benefits that exceed those induced by the placebo alone.
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