The placebo effect has been controversial throughout history. Notable medical organizations have endorsed it, but in 1903 Richard Cabot concluded that it should be. The nocebo response; The Nocebo Effect: Placebo's Evil Twin; What modifies a healing response; The science of voodoo: When mind attacks body, New Scientist. Placebo Effects: Understanding the mechanisms in health and disease: 9780198705086: Medicine & Health Science Books @ Amazon.com. 1996 Oct;49(10):1079-84; discussion 1085, 1087. Vitamin C, the placebo effect, and the common cold: a case study of how preconceptions. Placebo Effect. Placebo Effect. What is a placebo? A placebo (pluh- SEE- bow) is a substance or other kind of treatment that looks just like a regular treatment or medicine, but is not. It’s actually an inactive “look- alike” treatment or substance. This means it’s not a medicine. Typically, the person getting a placebo doesn’t know for sure that the treatment isn’t real. Sometimes the placebo is in the form of a “sugar pill,” but a placebo can also be an injection, a liquid, or even a procedure. It’s designed to seem like a real treatment, but doesn’t directly affect the illness. What is the placebo effect? Even though they don’t act on the disease, placebos affect how some people feel. This happens in up to 1 of 3 people. A change in a person’s symptoms as a result of getting a placebo is called the placeboeffect. Usually the term “placebo effect” speaks to the helpful effects a placebo has in relieving symptoms. This effect usually lasts only a short time. It’s thought to have something to do with the body’s natural chemical ability to briefly relieve pain and certain other symptoms. But sometimes the effect goes the other way, and the placebo seems to cause unpleasant symptoms. These may include headaches, nervousness, nausea, or constipation, to name a few of the possible “side effects.” The unpleasant effects that happen after getting a placebo are sometimes called the nocebo effect. Together, these 2 types of outcomes are sometimes called expectation effects. This means that the person taking the placebo may experience something along the lines of what he or she expects to happen. If a person expects to feel better, that may happen. If the person believes that he or she is getting a strong medicine, the placebo may be thought to cause the side effects. The placebo does not cause any of these effects directly. Instead, the person’s belief in or experience of the placebo helps change the symptoms, or changes the way the person perceives the symptoms. Some people can have the placebo effect without getting a pill, shot, or procedure. Some may just feel better from visiting the doctor or doing something else they believe will help. This type of placebo effect seems most related to the degree of confidence and faith the patient has in the doctor or activity. The placebo effect can make some treatments seem like they help certain symptoms, when in fact they do nothing to directly cause a change in the disease. Other factors that are sometimes lumped in with the placebo effect can also make a treatment appear to help even when it does nothing for the illness. These are discussed in the section called “Other things that can add to or be confused with the placebo effect.”How are placebos used in research? Placebos may be used in clinical trials. Clinical trials are research studies testing new drugs or other treatments in volunteers. Before a new treatment is used on people, it’s studied in the lab. If lab studies suggest the treatment will work, the next step is to test it on animals. If that also gives promising results, it may then be tested in clinical trials to see if it has value for humans. The main questions the researchers want to answer are: Does this treatment work? Does it work better than what we’re now using? What side effects does it cause? Do the benefits of the treatment outweigh the risks? Which patients are most likely to find this treatment helpful? If standard treatments for the disease are already available, the new treatment is usually compared to one of them. Placebo Effect for Pain Posted by Steven Novella on March 2, 2011. It has long been recognized that there are substantial multifactorial placebo effects that create. Placebo effects plus disease natural history and regression to the mean can result in high rates of good outcomes, which may be misattributed to specific treatment. The placebo effect happens when you decide a therapy will make you better and your belief makes it so. Is the placebo effect real or is it in your head? Placebo is a reflection of the meaning and context both patient and doctor ascribe to treatment. What can placebo tell us about our innate ability to heal? This tells researchers if the new treatment is as good as or better than the one that’s currently available. If there’s no approved treatment for an illness or condition, some people in the study may be given a placebo, while others get the new treatment being tested. The main reason to have a placebo group is to be sure that any effects that happen are actually caused by the treatment and not some other factor. The placebo looks, tastes, or feels just like the actual treatment, so that the patient and doctor’s expectations don’t affect the outcomes. The placebo control makes it possible to “blind” patients and doctors to which treatment they’re getting. This is called a double- blind controlled study, and neither the volunteers taking part in the study nor their doctors know who’s getting which treatment. This study design helps avoid biases in measuring outcomes that can be caused by the researchers or the patients’ expectations about the treatment. This is not as big a problem in studies of cancer treatment, where objective outcome measures are most often used. It’s more likely in studies that require patient reporting for symptoms like depression, sleeplessness, or pain. If you would like to know more about clinical trials, see Clinical Trials: What You Need to Know. People in a study using a placebo must always be informed that there’s a chance they could be getting the placebo. Please read Informed Consent for more on this. Those who get placebos in medical studies serve an important role. Their responses help provide a good way to measure the actual effect of the treatment being tested. The placebo group provides an important baseline with which to compare the treatment group. It helps researchers see what would have happened without the treatment, though both groups may still have some short- term effects based on what the patient expects. For instance, illnesses that sometimes go away on their own might be thought to get better because of the medicine, unless there’s a placebo group and those people get better too. On the other side, bad effects that were going to happen anyway, or that occur from some unrelated cause, may be blamed on the treatment unless they also happen to people in the placebo group. How does the placebo effect work? In the past, some researchers have questioned whether there’s convincing proof that the placebo effect is a real effect. But there are studies showing that the placebo effect is real in some situations. For example, scientists have recorded brain activity in response to placebo. Since many scientific tests have shown that there is a placebo effect, it’s one way we know for sure that the mind and body are connected. Some scientific evidence suggests that the placebo effect on pain may be partly due to the release of endorphins in the brain. Endorphins are the body’s natural pain killers. But it appears there’s more to it than this. The expectation effect. Many think the placebo effect occurs because the patient believes in the substance, the treatment, or the doctor. The patient’s thoughts and feelings somehow cause short- term physical changes in the brain or body. The patient expects to feel better, and so he or she does feel better for some time. But even if a person feels better after taking a placebo, it doesn’t mean the person’s illness or symptoms were not real. For instance, the person may feel less anxious, so stress hormones drop. Taking a placebo may change their perception – for example, a person might re- interpret a sharp pain as uncomfortable tingling. The placebo effect even plays a role in mainstream medicine. There’s evidence to suggest that what a patient expects about real medicines can influence how the patient feels after the medicine is taken. Even though responses from real drugs aren’t typically thought of as placebo effects, some short- term effects are affected by expectations – good ones as well as bad. Many people feel better after they get medical treatments that they expect to work. But the opposite can also happen, and this seems to support the idea of the expectation effect even more. For example, in one study, people with Alzheimer disease got less relief from pain medicines. These patients required higher doses – possibly because they had forgotten they were getting the drugs, or they forgot that the pain medicines had worked for them before. This suggests that past experiences also play into the placebo effect. The conditioning effect. In one study that looked at the placebo effect in pain relief, one group got a real pain medicine and the other did not. In the following days, both groups were given a placebo that looked like the real pain medicine. Those who had gotten the real pain medicine were able to tolerate more pain than those who had not gotten pain medicines before. In the same study, people who were given a drug that raised a certain hormone level beforehand actually had a similar (but smaller) hormone response when they were given a placebo later. Those who had not gotten the real drug beforehand had no change in their hormone levels when they got the placebo, even though they were told that they would. This helped to separate the power of the researcher telling them they would have an effect from the learned experience of having the effect in the past. This type of learned response after personal experience is called the conditioning effect. It seems to be part of what we call the placebo effect. The nocebo effect. The nocebo effect, in which a person has more symptoms or side effects after a placebo, is still being studied. Researchers believe it may be partly explained by a substance in the body that sends messages through the nerves. When a person is anxious, for instance, the substance is activated and the person feels more pain than a person who isn’t anxious. The nocebo effect can be seen in the brain: brain- imaging studies have shown that pain is more intense when a person expects more pain than when they don’t. This is linked to changes in certain brain regions on the imaging studies. The mind- body connection. Although we may not know all the ways it might work, the idea that the mind can affect the body has been around for thousands of years and is well- proven for certain situations. Many ancient cultures depended on mind- body connections to treat illness. Shamans or medicine men would not have viewed their efforts as placebos.
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