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Placebos Prove So Powerful Even Experts Are Surprised; New Studies Explore The Brain's Triumph Over Reality

Excerpts of article: by Sandra Blakeslee, the New York Times October 13, 1998 Pg f1

Studies have shown that placebos can work wonders. Like "real drugs" they can cause side effects like itching, diarrhea and nausea. They can lead to changes in pulse rate, blood pressure, electrical skin resistance, gastric function, penis engorgement and skin conditions. The question is, why?

Explanations of why placebos work can be found in a new field of cognitive theory- what the brain believes about the immediate future. Like classical conditioning theory (Pavlov's dogs salivate at the sound of the bell), expectancy involves associative learning.

Support for the expectancy theory emerged about ten years ago, when many scientists realized how closely the brain, the immune system and the hormone production of the endocrine system are linked. Chronic stress sets into motion a cascade of biological events involving scores of chemicals in the body-serotonin, cortisol, cytokines, interleukins, tumor necrosis factor and so on.

Such stress lowers resistance to disease and alters gene expression. When people are under stress, wounds heal more slowly, latent viruses like herpes erupt and brain cells involved in memory formation die off.

But, what about the opposite? Can a thought or belief produce a chemical cascade that leads to healing and wellness? Researchers studying placebos think the answer is yes, and they offer several ways it might work:

  1. A placebo might reduce stress, allowing the body to regain some natural, optimum level of health.

  2. Special molecules may exist that help carry out placebo responses. For example, a recent study found that stressed animals can produce a valium-like substance in their brains, but only if they have some control over the source of the stress. People almost certainly have similar brain chemistry.

  3. Placebos may draw their power from the way the brain is organized to act on what experience predicts will happen next.

Dr. Marcel Kinsbourne, a neuroscientist at the New School for Social Research in New York, explains it this way: The brain generates two kinds of activation patterns, which arise from networks of neurons firing together. One type is set in motion by information flowing into the brain from the outside world- smells, tastes, visual images, sounds. At the same time, the cortex draws on memories and feelings to generate patterns of brain activity related to what is expected to happen.

The top down patterns generated by the cortex intersect smoothly with the bottom-up patterns to inform us about what is happening. If there is a mismatch, the brain tries to sort it out, without necessarily designating one set of patterns as more authoritative than another.

The expectations that result are internally generated brain states that can be as real as anything resulting purely from the outside world.


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