Placebo is the Latin term for the phase, “I will please.” Throughout medical history, the placebo effect was the principal treatment that shamans, witch doctors, spiritual healers, and even physicians offered. The effect occurred through reassurance, attention, and belief in treatment, that would suggest to patients that they had powers to fight their illnesses. These procedures are still used in many indigenous cultures that rely on shamanistic healing that places healing power in objects and rituals. In fact, placebos are sometimes called sham treatments. It should never be believed that these sham treatments as practiced in some cultures do not have positive effects. In his book, Mind Game: Witch Doctors and Psychiatrists, E. Fuller Torrey made the case that his aim was not to dismiss the role witch doctors play because he credited them with some success in treating patients. He made a more compelling case for what they did by comparing their results against those obtained by psychiatrists. According to some medical historians, from the early 1800s through as late as World War II, placebos (usually in the form of sugar pills or saline injections) were regularly prescribed for up to 80% of patients. Doctors used placebos to appease patients when no effective treatment for their symptoms was available, or prescribed placebos to patients they perceived as difficult. There were surely used, and are likely used even now, when physicians and other medical personnel were/are unable to determine the diagnosis of the symptoms presented by a patient, yet still wish to provide some type of treatment even if it a placebo.
A placebo generally refers to any medical or behavioral treatment that it inert, but it can also refer to changes that occur because suggestion in one form or another is incorporated into the protocol. Placebos have long been used in research to objectively test the efficacy of a new behavioral or health care treatment, such as a drug. In the latter, for example, one group of people takes the drug (the experimental group) while another group (the control group) takes the placebo, an inactive pill. In medicine, a placebo appears to look exactly like a real drug but is made of an inactive substance such as a starch or sugar. None of the participants in these trials know whether they are taking the active or inactive substance; sometimes, in fact, not even the researchers know which drugs are active and which are not (this is referred to as a double blind test).
By themselves, placebos can result in or be coincidentally associated with many changes, both desirable and undesirable. The placebo effect appears to have two components: anticipation of results, usually positive, from taking a drug (sometimes called suggestibility); and spontaneous change where people’s health improves spontaneously and without treatment. If spontaneous change—whether positive or negative—occurs after a placebo is taken, the placebo may incorrectly be credited with or blamed for the result. There are several factors, which likely influence the placebo effect including,
• Characteristics of the placebo. If the pill looks genuine, perhaps the same in appearance as the drug being tested, the person taking it is more likely to believe that it contains medicine. It is desirable that both the active and inactive pills appear the same. Although patients will only know the characteristics of the specific pill they take, it is likely that they will talk to others involved in a trial if they know who they are. Characteristics of the drug may be a topic of discussion for both parties when waiting to see the experimenter. There is research that shows larger sized pills suggest a stronger dose than smaller pills, and that taking two pills appears more potent than swallowing just one. As might be expected, injections generally have a more powerful effect than pills.
• Attitude of the person. If a volunteer for a study expects the treatment to work, chances are that the placebo effect will be stronger. Research indicates that the placebo effect may still take place even if the person is skeptical of success. It is impossible to totally eliminate the possibility of a placebo effect: in the recruitment of subjects, the investigator has to explain the purpose of his study to determine the interest of a potential subject in the trial. This often suggests that the scientist is testing a new drug or behavioral treatment that may make a patient with a chronic condition feel better. Through the power of suggestion, this automatically plants the seed in the person that, by volunteering for the study, he or she is going to benefit from participating in the study.
• Researcher-patient relationship. If you have a good relationship with whoever is conducting the study, particularly if it is your trusted doctor, you are more apt to think that whatever treatment you are going to receive will help you. After all, this is a person who has helped you in the past. Why should he or she do anything to fail you now? You may feel that way about anyone who you perceive in a positive. Even if assigned to a control group, you expect something positive to occur, which may result in the placebo effect.
How placebos work
The exact physiological mechanisms of the placebo effect remain unknown. However, there are a number of hypotheses as to why it occurs, including:
• Suggestibility. The basic definition of suggestibility is how you accept and act on suggestions by others. If you are highly suggestible, taking any kind of pill may bring relief. This can result in a potent placebo effect. The explanation of suggestibility is far more complicated than the basic definition of a placebo. Suggestibility depends upon a variety of variables, including past experiences that are unique to each individual.
• Spontaneous change. Many acute disorders, such as the common cold, are self-limiting. They resolve themselves, with or without placebos or drugs, and the end of symptoms is merely coincidental to the presentation of another stimulus. The changes that occur may not be perceived as natural, but the result of adding some sort of drug or treatment when the occurrence of the events was purely coincidental.
• Changes in phenomena. The symptoms of chronic illnesses vary. A patient with asthma, for example, may breathe fine one day, but experience an attack the next day. This reflects that his or her wax-and-wane (the entire process of our breathing, in fact, can be regarded as a state of steady state variability in that a measurement taken one moment is likely to be different the next moment). A change in symptoms that occurs when given a placebos is apt to be coincidental, and not due to the placebos at all. This effect is often referred to as spontaneous improvement. Changes in the behavior of individuals also occur daily. If certain changes occur with the presentation of a placebo, the latter may be credited with the change when it actually was not.
• Changes in perception. Changes in the perceptions people have of their condition at any time may change as a result of taking a placebo. They may feel that a migraine they experience, for example, is not as severe as those they experienced in the past. No active ingredient has been added to their regimen; they may just believe this to be the case. Hence, the placebo effect. Patients may also perceive that a placebo reduces the anxiety or depression that may accompany a chronic condition.
• Visualization. A patient’s visualization of a scene where his or her health is improved may also produce a placebo effect. Research indicates that this type of visualization produces an altered state where the brain responds to an imagined scene in much the same way as it responds to an actual scene. A placebo may help the brain to remember a time before the onset of a chronic illness and bring about physiological change. This theory is often referred to as “remembered wellness.”
• Brain chemicals. A person's beliefs, perceptions, and hopes about a treatment, combined with suggestibility, may have a significant biochemical effect. Sensory experience and thoughts can affect neurochemistry. The body's neurochemical system, in turn, affects and is affected by other biochemical systems, including the hormonal and immune systems. It has long been reported that placebos may trigger the release of the body's own natural painkillers, the brain chemicals (neurotransmitters) known as endorphins. The mechanism by which this occurs is unknown, but it appears correlated with the perceptions, suggestibility, and beliefs of patients.
• Individual reactions. Some people seem more susceptible to the placebo effect than others. People who have a positive opinion of drugs, doctors, nurses, and hospitals are more likely to respond favorably to placebos than are people who have a negative opinion of these factors. It has been noted that some people who are particularly susceptible to placebos tend to become compulsive about using the drug; they tend to increase the dose, and develop withdrawal symptoms when they are deprived of the placebo. However, this may be part of being suggestible and weakly linked to the placebo per se.
• Additive effects of placebos. Beneficial effects of additional treatment may improve medical care. Research trials described as placebo-controlled are actually following an additive design—both the active treatment and the placebo group are receiving additional supportive therapies. There are arguments both for and against the use of placebos.
Benefits are that the placebo effect is usually positive by its nature because it indicates that a patient believes in the therapy, and the therapy is having some sort of a beneficial effect. In addition, the placebo effect has been documented in a wide variety of diseases and disorders over the centuries. There have been reports over the centuries that they had positive effects on certain conditions such as headaches, arthritis, and asthma. Much of the effect on these conditions, however, is likely associated to the impact of suggestibility on individual patients. There is evidence that between 30 - 60% of patients with illnesses ranging from arthritis to depression report a substantial improvement in their symptoms after receiving a placebo. Much of the evidence on the placebo effect sometimes be of dubious scientific merit, but that doesn’t matter: if the patient believes it helps him or her, that’s all that matters.
Harmful effects. These are often described in research as the "nocebo" phenomenon, the evil twin of the placebo effect. While the placebo effect refers to health benefits produced by a treatment that should have no effect, patients experiencing the nocebo effect experience the opposite. They presume the worst, and that's just what they get. This is, in other words, a self-fulfilling prophecy. Unwanted side effects can also occur with use of placebo. Effects have includes nausea, drowsiness, and allergic reactions, such as skin rashes, have been reported. Critics of placebos maintain that deception is wrong, regardless of whether the deceived patient experiences an end to their symptoms. Finally, a report released in 2001 reviewed 114 studies where use of a placebo was compared to both treatment and no treatment and found no placebo effect with respect to measurable medical conditions, such as blood pressure and cholesterol levels. In such studies, however, the responses of individual patients is masked by statistical methods used to analyze the study.
COMMENTS: While arguments still occur as to whether or not the placebo effect is real, the overall evidence supports the conclusion that it is real. This is based on three points. First, to disprove there is no placebo effect requires that no physiological changes occur with the taking of inert pills or fake conditions. There are too many data to show that physiological changes often do occur, however. Second, any procedure that involves suggestibility is apt to change behavior. It is a potent change variable in and of itself. As long as there are individual differences among people with respect to suggestibility, this will be the case. Finally, it is impossible to totally exclude suggestibility and the potential for a placebo effect from any medical or behavioral intervention research. There are just too many variables, including an investigator’s explanation of the research that can suggest to the patient that he or she will respond to whatever stimulus is presented in a way that increases the likelihood of a placebo effect. Fortunately, in many cases the interaction of these variables likely diminishes the placebo effect across groups of individuals. Even then, however, it cannot be totally eliminated.
Do you have any comments on the placebo effect?
Reference: E. Fuller Torrey. Mind Game: Witch Doctors and Psychiatrists. New York: Macmillan, 1979.
Tom Creer