placebo effect

Research performed at the University of Copenhagen and the Nordic Cochrane Center, Rigshopitalet, Denmark studied statistics from over 700 trials that included tests of pharmacological, physical and psychological placebos.

When going through the results that involved some 7,500 patients, the researchers excluded all tests that did not compare placebo and no treatment at all. They then reviewed how the test subjects receiving no treatment compared to those receiving placebos.

The result was that there were little or no difference. "We found little evidence in general that placebos had powerful clinical effects" the researchers wrote. Only in the treatment of pain could a significant placebo effect be statistically verified.

This supports the theory that the placebo effect is based upon earlier experiences and expectations. The body simply produces more endorphins since this may have been the result of a previous pain medication, such as morphine. This kind of effects may however be negative, nocebo effect.

Source: Scientific American, ne.se

A lot of people mistake the placebo effect for alternative medicine, which is something different. It is common medical pratice to prescribe a placebo to a patient who thinks he or she *needs* medication.

It's also of paramount importance in pharmaceutical research, when new drugs are being tested it is important to filter out any other influence than the drug itself. This is done by blind or double-blind testing, in the former the patient doesn't know it's been given a placebo, in the latter the doctor giving the drug doesn't know he or she is giving a placebo(to filter out the influencing of a second person). Studies have found placebo effects with lots of medication, and these are renown researches.

Studies show a large negative correlation between the amount of stress (for a prolonged period) and the number of white blood cells in the blood. A proof that stress has a negative impact on the body's defence system. There's also lots of research on changes on a neurochemical level due to psychological changes, providing evidence of physical changes due to mental changes. It is all a matter of neuro-chemistry and mind. Wether one influences the other or vice versa is a different discussion.

I don't have access to the text of the study, but the Journal of the American Medical Association reports that the study was a survey of clinical drug trials in which there were both placebo and no treatement control groups, and compared the effectiveness of those two courses of action. What they found, apparently, was that for most of the 114 studies cited, there was little or no benefit to taking placebos over avoiding treament altogether. The summary continues,

"Placebos did appear to produce small benefits in studies in which the outcome being measured was subjective and continuous, and in trials of pain treatment."

Now, while this clearly warrants further investigation, it is not quite a damning condemnation of the classical notion of the placebo effect. The vast majority of clinical drug trials don't include both placebo and zero treatment control groups; and a good many studies these days don't include a placebo group at all -- often new drugs are compared to a control group that uses an existing treatment regime, for obvious ethical reasons. I believe I read a news item when the study was published that the researchers had to wade through over 8,000 studies to find the 114 they analyzed for their work. We cannot, therefore, assume that the coverage of study was broad or comprehensive. This is the normal process of science; while popular media likes to make strong statements about the results of this study or that, careful science takes small, measured steps, preferring a strong degree of confidence in a small step over a weak degree of confidence in a bold sweeping conclusion.

Certainly the placebo effect has been the subject of study before, and in the end a thorough discrediting of the placebo effect will have to come up with a well-documented and careful explanation for those results, either through methodological analysis of past studies or by finding a balance between the ideas that the placebo effect is huge and that the placebo effect doesn't work.

The Placebo Effect on Pain
Following is a description of how one goes about demonstrating this effect as well as an investigation of the chemical mechanism

The lovely young subjects are told that they will be participating in a trial to test the effects of a pain killer on their pain threshold. They then allow the professional researcher to slip a fairly thick needle into the vien in the crook of the elbow.

"I'm going to stomp on your foot now, Cassandra, and I want you to rate the pain on a scale from one to five," whispers the good scientist.
The scientist stomps and she screams "four."
"Igor, flip the switch to that pump over there. You are now receiveing the pain killer, Cassandra. In a moment I will again stomp on your foot, and perhaps with the fury of MethRat." (saline, merely, is pumped into Cassandra)
The scientist exerts a fair amount of force, and suddenly too, on the poor girl's foot, to which she replies "Two."
"You will now receive another dose of pain killer, young lady," hisses the scientist with an arbitrary amount of triumph. (Igor switches on the pump again, however this time Cassandra receives a dose of Naloxone.

Naloxone is an opiod antagonist. Opiods include heroin, hydrocodone(codeine), and methadone, as well as the endogenous endorphins.

"Again, Cassandra, I shall drive my heal into your soft pink toes," murmurs the scientist. This being done, she screams forth a number, and that number is Five.

Could she have been merely responding to what was expected of her? Perhaps her previous experience with pain killers had conditioned in her a response to release endorphins.

But perhaps, sweet Cassandra's belief effected the release of endorphins, which then inhibited her pain sense. And so when she was given Naloxone, those endorphins were blocked. Could it be, then, that belief is realized chemically?