Placebo

The term placebo appears in a 1785 New Medical Dictionary (2nd edition). Derived from Latin meaning “I will please” or “satisfy,” placebos [Page 1385]and the placebo effect are evolving concepts. A placebo has alternatively been defined as an empathetic intervention, a treatment, and an ostensibly inert substance.

In ancient Babylonia, Assyria, India, Greece, China and Rome, treatments like drugs, magic, religious rituals, prayer and physical therapy are now understood by some researchers as placebos. Some Western medical historians even attribute the efficaciousness of all earlier medical treatments to the placebo effect. Different definitions of placebo and the placebo effect reflect competing philosophies of science and medicine.

By the 1930s, placebo controls evolved from interventions in single-blind studies to double-blind clinical trials. In these studies, a placebo is said to depend on the receptivity or suggestibility of the ill person and on the interpersonal skills of the healer. If causal explanations are valued, the placebo effect has been described as an unexpected outcome.

If the placebo effect is a direct or indirect therapeutic outcome of a biomedical procedure, some exclude it from further consideration on the grounds that it is an impurity. Other authorities contend that studies of the placebo effect before the mid-1990s were unsystematic and, therefore, that generalizations from them need be regarded with caution. In an emerging trend, some researchers contend that no substance is truly inert.

Accordingly, clarity about the context for the placebo effect enhances understanding of the effectiveness of holistic medicine, mind-body self-healing, and cognate traditions like acupuncture and qigong that unblock and redirect a patient's energy.

If medical investigators believe that an experimental treatment is beneficial, then the use of placebos in double-blind studies may not always contribute to the well-being of patients in the control group. Yet eliciting informed consent from human subjects in clinical probably exposes them to favorable influences. In this respect, evidence-based medicine remains at a quandary.