Sham treatment

A placebo (/pləˈsiːboʊ/ plə-SEE-boh; Latin , "I shall please" from , "I please") is a substance or treatment with no active therapeutic effect. A placebo may be given to a person in order to deceive the recipient into thinking that it is an active treatment. In drug testing and medical research, a placebo can be made to resemble an active medication or therapy so that it functions as a control; this is to prevent the recipient(s) and/or others from knowing (with their consent) whether a treatment is active or inactive, as expectations about efficacy can influence results. This psychological phenomenon, in which the recipient perceives an improvement in condition due to personal expectations, rather than the treatment itself, is known as the placebo effect or placebo response. Research about the effect is ongoing.

Placebos are an important methodological tool in medical research. Common placebos include inert tablets (like sugar pills), vehicle infusions, sham surgery, and other procedures based on false information. There is also some evidence that patients who know they are receiving a placebo still report subjective improvement in their condition if they are told that the placebo can make them feel better. It has further been observed that use of therapies about which patients are unaware may generally be less effective than using ones that patients are informed about, regardless of whether or not a placebo is involved.

Placebo effects are the subject of 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 effects on physiological changes in the brain. Placebos can produce some objective physiological changes, such as changes in heart rate, blood pressure, and chemical activity in the brain, in cases involving pain, depression, anxiety, fatigue, and some symptoms of Parkinson’s. In other cases, like asthma, the effect is purely subjective, when the patient reports improvement despite no objective change in the underlying condition.

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