Wednesday, March 30, 2005

Does chronic fatigue syndrome involve a neuropsychiatric failure of the placebo mechanism?

The New York Times > Health > For Chronic Fatigue, Placebos Fail the Test
Studies suggest that placebos relieve the symptoms for about 30 percent of patients suffering from a wide variety of illnesses. Migraine headaches, for example, respond at a rate of about 29 percent to placebo treatment, major depression at about 30 percent and reflux esophagitis at about 26 percent.

In some diseases, placebo treatments are even more effective - 36 to 44 percent of patients with duodenal ulcers improve on placebos, depending on how many of the treatments are offered each day.

But by pooling results from more than two dozen studies, the researchers, led by Dr. Hyong Jin Cho, a professor of psychiatry at King's College London, found that, among people with chronic fatigue syndrome, only 19.6 percent responded to placebos, not the 50 percent found by previous, less systematic studies.
Two NYT articles this month based on the same issue the Journal of Psychosomatic Medicine? Good for them!

This is tantalizing. The article quotes researchers arguing that this proves CFS is "organic". Phaw. To a reductionist everything is "organic" -- including joy, sadness, laziness and all varieties of fatigue. The question is really about mechanism and intervention. Most pain and suffering syndromes, including fairly severe angina (this was shown in a famous and impossible-to-replicate study of a sham surgical intervention for severe angina) respond very well to placebo. In general anything that is "perceived" by the brain responds to placebo. In contrast malignant melanoma does not respond to placebo (though pain due to MM will).

Many of the symptoms of CFS are things that live in the brain -- sensations of tiredness, fatigue, malaise. They ought to respond to placebo. If they don't then one wonders if the pathophysiology of CFS somehow degrades the normal placebo response.

One interesting study would be to take a group of people with CFS, inflict an ethical amount of discomfort, and give half a placebo and half a pain medication. Do the same thing for a control group. It would be interesting to compare the therapeutic gap in both cases.

Maybe when we understand the neurophysiologic basis for the placebo response, we'll understand CFS.

Hmm. That's a lot of speculation ...

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