Saturday, January 17, 2009

Homeopathy and the placebo effect

This week on eSkeptic, the email newsletter of the Skeptics society, Dr. Harriet Hall takes on homeopathy in an article aptly titled "Homeopathy -- Still Crazy after all These Years." Why, she asks, should this long-debunked pseudoscience still remain popular (and practiced, amongst others, by Queen Elizabeth and Prince Charles)? Hall writes that

Oliver Wendell Holmes recognized that it was nonsense back in 1842 when he wrote “Homeopathy and Its Kindred Delusions.” We long ago gave up the nonsense of trying to balance the four humors by bloodletting and purging, but the homeopathy Energizer Bunny is still marching on. What makes it so indestructible?

What, indeed? Homeopathy is based on the idea that "like cures like" so homeopathic treatments are highly diluted substances that cause the original ailment (Hall gives the example of coffee--homeopaths say that if coffee keeps you up at night, drink diluted coffee and hey-presto! You will get better.) Things get more suspect when we consider the amount of dilution. "How dilute?" Hall asks. Well, seriously dilute,

as in comparable to one drop diluted in all the water on Earth. When they realized that no molecules of the original substance were left in most homeopathic dilutions,homeopaths rationalized that the water must “remember” what it had come into contact with — as in clusters of water molecules somehow holding the memory of their encounters with the allegedly curative substances. Unfortunately, homeopaths have failed to explain how water can remember what it’s supposed to remember, and forget all the other memories of coming into contact with various trace contaminants, elements, bacteria, and whatever else happened to float by at the time.

Essentially, homeopathy is, as Hall says, "the ideal placebo. It’s great for the worried well and the hypochondriac. It’s great for those elusive symptoms scientific medicine cannot diagnose and cure. It’s harmless except in cases where patients are persuaded to forgo effective medical treatment, or when homeopathic vaccines are offered in lieu of real vaccines."

In other words, homeopathy "works" because people suspend their disbelief and trick themselves into thinking it is somehow, mysteriously, medically effective. They talk to a sympathetic homeopath who listens, seems to care, and spends time working with the patient. Homeopathy appears to work because patients report that "they feel better. That’s why bloodletting and purging lasted so long: patients got better despite the treatment and the treatment got the credit." It is only a matter of time before homeopathy is tossed out as well.