"The Placebo Response" by Howard Brody

This is the best book on the placebo response that I have come across. It is written by a medical doctor and researcher and was published in the year 2000. All the placebo examples he gives were originally published in various medical journals.

The placebo response occurs when expectations developed by the brain affect body processes. The biochemical pathways that accomplish this are an active area of research but at least the general outlines are clear. The author mentions three major pathways: the endorphin (pain relief) pathway, the stress - relaxation pathway, and the psychoneuroimmune pathway. In practice these pathways overlap to a considerable degree with the general term for these chemical messengers being called cytokines . They interface with the brain via the hypothalamus - pituitary gland and via the vagus nerve (and probably others).

The author calls whatever chemicals are responsible for the placebo effect the "inner pharmacy" which makes sense when one considers that all drug work by connecting to certain cellular receptor sites and that those sites only exist to bind to the body's own inner chemicals.

The author mentions that doctors prior to the 1940's frequently depended on using the placebo response to heal patients. They often made up their own medicines for this. Healing instead of truth was the basis for medical ethics then. Yet this meant patients often did not trust their doctors and this could lead to sad consequences. The author gives an example of a negative placebo (Nocebo) response.

A patient was in a hospital for some tests. She had a mild congestive heart condition that was stable due to medication. The senior cardiologist came into her room with a bevy of students and interns and said out loud that she had TS (tricuspid stenosis). The patient interpreted that to mean "Terminal Situation". Within hours her lungs began filling with fluid as she displayed a general anxiety response. No matter how much the staff told her that TS did not mean "terminal situation" she would not believe them since "you doctors never tell the truth". She died that evening.

On average a third of all people in a study will have some level of placebo response. Medical drug are only approved as effective if they are better than the placebo response. The placebo response is a real effect and it was the best form of healing ancient humanity had and it can still be useful today.. but probably not by normal medical doctors who now must be truthful about everything. This would seem to open up a place for alternative healing practioners if done in coordination with regular doctors.

The placebo response exists in other animals besides humans. Rats can develop simple expectations based upon classical conditioning. In the 1980's Dr. Robert Adler did an experiment in which he gave rats an immune system suppressing drug called cyclophosphamide combined with the artificial sweetener saccarine on various classical conditioning schedules. When the training was complete and the rats only received saccarine their immune system decrease was almost as strong as with cyclophosphamide!

For many more placebo response examples read the book.