- Placebos can work even if one knows the pill is inactive.
- Certain genes may make the placebo effect more likely for specific conditions.
- IBS, migraine, insomnia, and some cancer side effects respond especially well to placebos.
Even if there’s nothing in a pill but a bit of sugar, it can cut symptoms. This phenomenon—when your physical state changes simply because you associate something with caring and good health--is called the placebo effect. Anything can inspire it—a prayer, a ceremony, a drink, or a little white pill.
This does not mean you didn't have a "real" illness. The mind is part of the body and changes in your mental state affect other parts of your body—and vice versa.
The main disadvantage is the happy effect often doesn't last. It also doesn't work consistently. So far, placebos seem most effective for pain, including irritable bowel syndrome and migraine, as well as stress-related insomnia and cancer side effects like fatigue and nausea. They may also be more effective in people with certain genes.
The growing effectiveness of placebos
Interestingly, the placebo effect has gotten stronger over time. When McGill University scientists analyzed 84 clinical studies of drugs for pain relief, they discovered that in the more recent studies volunteers were more likely to report relief from placebo—on average about 30 percent cuts in pain. Because this wasn’t true outside the U.S., the researchers looked for unique features of the American market. One stands out: Americans are exposed to advertising for drugs, which only New Zealand also allows.
There has also been a trend of growing effectiveness in placebos in studies of antidepressants and antipsychotic drugs.
Irritable bowel syndrome (IBS), which may affect as many as 15 percent of the U.S. population, is hard to treat. But nearly 40 percent of patients react well to placebos. That’s true even if they know they’re getting a sugar pill: In one set of studies, patients who knew that they were taking a placebo reported twice as much improvement, including relief from bloating, painful cramps, and diarrhea, than the untreated patients in the control group. “Some of the patients came back and asked for more (fake) pills,” the study noted. There has been some success with placebos for treating depression.
Doctors already give prescriptions simply to trigger a placebo effect—in one survey in the United Kingdom 77 percent of doctors reported that they do so—but without telling patients.
Open-label placebos and genetics
A new type of study now uses what are called open-label placebos—in which the patients know they are receiving placebos. One overview found that open-label placebos were effective in tests related to back pain, attention deficit hyperactivity disorder (ADHD), allergic rhinitis, and menopausal hot flashes, as well as cancer-related fatigue and IBS.
Not everyone benefits—the impact of placebos varies from one person to the next. This may be a genetic trait. One study found that a particular gene variation makes people more sensitive to IBS pain and those same people were more likely to find relief from a fake acupuncture treatment.
At the University of Alabama in Birmingham, researchers explored the impact of the same gene on cancer-related fatigue and concluded that it promoted relief in response to an open-label placebo. The gene provides instructions to brain nerve cells to produce a particular enzyme.
Future research into how placebos work
Neuroscientists have begun to look in more detail into how the brain operates to produce beneficial responses to a placebo. Doctors and patients—and of course, parents—know that when sick people hear “This is going to make you feel better” and trust the speaker, they are more likely to have a good response than if they aren’t reassured or don’t believe what they hear.
There is some debate about whether placebos work in people who have Alzheimer’s disease. The disease impairs the prefrontal cortex, which is associated with thinking, behavior, and emotions, and people with the condition may be unable to develop expectations when they take a pill. However the Alzheimer’s Association argues that tests of drugs for this condition should include a placebo group, as with all tests.