The Scientific Study of Placebo Effects in Animal Models

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Placebo effects in animal models have been studied for many years, and some researchers are finding that some types of drugs actually work better in laboratory animals than they do in people. If you have ever used treatment for a disease, or if you were an aspirin addict, you may have had the experience of wanting to swallow a box of the stuff just before you needed it. This is the placebo effect in action. Now scientists know why that happens, and they are beginning to find methods of reversing it. Here’s why.

Placebo Effects in Animal Models

A close up of a horse

When people are asked if they actually know that they are taking placebos, the majority answer yes, but do they actually know how the medicine is working? Most people will say they can feel or taste the effect. There are even some who will claim to see lights in their eyes that aren’t there. These claims are all consistent with the idea that placebos actually work because the brain believes that something has changed. The serotonin levels in the brain drop to a low level, and a person feels the same way they would feel if they were under the influence of a particularly strong prescription pain reliever.

But how did this phenomenon take hold in animal models? Scientists had begun studying placebo effects in patients with serious illnesses long before they understood how they worked in patients. One scientist was studying the effect of penicillin on skin diseases. Another was researching the effects of Vitamin A in preventing eye problems.

To discover how these results came about, the scientist had to test various drugs on animals, just like he was testing them in patients. When the animals showed a response to the drug, that strengthened their evidence that the drug actually worked. Then he could test more drugs on the same animals and see what kind of response they gave. He could also test animals in other ways to see how they responded under placebo effects.

A Much Ado

A chicken standing in front of a fence

These studies confirmed what many patients had suspected all along: that when we place ourselves in a certain situation or in a condition that is not relevant to us, our brains tend to override the signals from the real world and think that we are in a “better” situation. In experiments with mice, for instance, the scientists repeated the same stressful event four different times, but in each test, the mice showed no change. So the scientists concluded that the mice simply ignored the four sessions. But by exposing the animals to the stressful situations again and showing that they ignore the situations, they have shown that the stress is actually removing the placebo effects from their brains. This is why doctors never let a patient continue any physical therapy or other treatments on their own, without supervision.

These are the types of tests that will show placebo effects in animals. For instance, in the pain-prevention test, the scientists found that the mice showed less pain after the third trial. But they did not know that the mice in the control group had been given pain killers previously and thus learned to expect less pain from that treatment.

Most animal models have very poor health histories, and most are fed by humans or chemicals in their food. Therefore, we cannot be sure how they will react to a new condition or to the administration of a new drug. For instance, the effects of chronic alcohol abuse on animal models can be very different from the effects of the same drug on humans because humans have good health systems that protect against alcohol’s long-term effects. Similarly, the effects of chronic nicotine abuse on animal models may be very different from the effects on humans.

Bottom Line

That’s why it’s important to carry out placebo effects testing in your own animal models. If you’re not sure how your own animal models will respond, you might want to carry out a number of tests or try a number of methods until you find the right one. And you should never just rely on the results of earlier animal models without checking them out yourself.