A placebo is a simulated or otherwise medically ineffectual treatment for a disease or other medical condition intended to deceive the recipient. Sometimes patients given a placebo treatment will have a perceived or actual improvement in a medical condition, a phenomenon commonly called the placebo effect. Placebo effect consists of several different effects woven together, and the methods of placebo administration may be as important as the administration itself.
In medical research, placebos are given as control treatments and depend on the use of measured suggestion. Common placebos include inert tablets, vehicle infusions, sham surgery, and other procedures based on false information. However, placebos may also have positive effect on a patient's subjective experience who knows that the given treatment is without any active drug, as compared with a control group who knowingly did not get a placebo.
Placebo effects are subject of recent scientific research aiming to understand underlying neurobiological mechanisms of action in pain relief, immunosuppression, Parkinson's disease and depression. Brain imaging techniques done by Emeran Mayer, Johanna Jarco and Matt Lieberman showed that placebo can have real, measurable effect on physiological changes in the brain. The objective physiological changes have been reported, from changes in heart rate and blood pressure to chemical activity in the brain, in cases involving pain, depression, anxiety, fatigue, and some symptoms of Parkinson’s, but in other cases, like asthma, the effect is purely subjective, when the patient reports improvement despite no objective change in the underlying condition.
Placebos are widely used in medical research and medicine, and the placebo effect is a pervasive phenomenon; in fact, it is part of the response to any active medical intervention.
The placebo effect points to the importance of perception and the brain's role in physical health. However, the use of placebos as treatment in clinical medicine (as opposed to laboratory research) is ethically problematic as it introduces deception and dishonesty into the doctor-patient relationship. The United Kingdom Parliamentary Committee on Science and Technology has stated that: "...prescribing placebos... usually relies on some degree of patient deception" and "prescribing pure placebos is bad medicine. Their effect is unreliable and unpredictable and cannot form the sole basis of any treatment on the NHS."
Since the publication of Henry K. Beecher's The Powerful Placebo in 1955, the phenomenon has been considered to have clinically important effects. This view was notably challenged when, in 2001, a systematic review of clinical trials concluded that there was no evidence of clinically important effects, except perhaps in the treatment of pain and continuous subjective outcomes. The article received a flurry of criticism, but the authors later published a Cochrane review with similar conclusions (updated as of 2010). Most studies have attributed the difference from baseline until the end of the trial to a placebo effect, but the reviewers examined studies which had both placebo and untreated groups in order to distinguish the placebo effect from the natural progression of the disease.
A placebo is anything that seems to be a "real" medical treatment -- but isn't. It could be a pill, a shot, or some other type of "fake" treatment. What all placebos have in common is that they do not contain an active substance meant to affect health.
How Are Placebos Used?
Researchers use placebos during studies to help them understand what effect a new drug or some other treatment might have on a particular condition.
For instance, some people in a study might be given a new drug to lower cholesterol. Others would get a placebo. None of the people in the study will know if they got the real treatment or the placebo.
Researchers then compare the effects of the drug and the placebo on the people in the study. That way, they can determine the effectiveness of the new drug and check for side effects.
What Is the Placebo Effect?
Sometimes a person can have a response to a placebo. The response can be positive or negative. For instance, the person's symptoms may improve. Or the person may have what appears to be side effects from the treatment. These responses are known as the "placebo effect."
There are some conditions in which a placebo can produce results even when people know they are taking a placebo. Studies show that placebos can have an effect on conditions such as:
- Sleep disorders
- Irritable bowel syndrome
In one study involving asthma, people using a placebo inhaler did no better on breathing tests than sitting and doing nothing. But when researchers asked for people's perception of how they felt, the placebo inhaler was reported as being as effective as medicine in providing relief.
How Does the Placebo Effect Work?
Research on the placebo effect has focused on the relationship of mind and body. One of the most common theories is that the placebo effect is due to a person's expectations. If a person expects a pill to do something, then it's possible that the body's own chemistry can cause effects similar to what a medication might have caused.
How Does the Placebo Effect Work? continued...
For instance, in one study, people were given a placebo and told it was a stimulant. After taking the pill, their pulse rate sped up, their blood pressure increased, and their reaction speeds improved. When people were given the same pill and told it was to help them get to sleep, they experienced the opposite effects.
Experts also say that there is a relationship between how strongly a person expects to have results and whether or not results occur. The stronger the feeling, the more likely it is that a person will experience positive effects. There may be a profound effect due to the interaction between a patient and health care provider.
The same appears to be true for negative effects. If people expect to have side effects such as headaches, nausea, or drowsiness, there is a greater chance of those reactions happening.
The fact that the placebo effect is tied to expectations doesn't make it imaginary or fake. Some studies show that there are actual physical changes that occur with the placebo effect. For instance, some studies have documented an increase in the body's production of endorphins, one of the body's natural pain relievers.
One problem with the placebo effect is that it can be difficult to distinguish from the actual effects of a real drug during a study. Finding ways to distinguish between the placebo effect and the effect of treatment can improve and lower the cost of drug testing. And more study may also lead to ways to use the power of the placebo effect in treating disease.