The Placebo Effect: An Update on What We Know


The placebo effect – one of the more baffling aspects of health and medicine.  It is, in essence, when you take a fake treatment and get real benefits.

Why getting a pill, for instance, with nothing in it but sugar can often make you feel significantly better, versus getting nothing at all, is a real mystery.

Fortunately, research continues to show more and more about how it works and why as well as what it means.  In particular, specific biochemical analysis has shown that the placebo effect has very real effects on the body that can be measured and analyzed.

The history

As a concept, the placebo effect stems from a mistranslation by St. Jerome of a Hebrew prayer, using the Latin word placebo, which means “I shall please,” instead of the Latin for “I shall walk.”

Those who would pray using this prayer, which was considered invalid, were called placebos.

This concept evolved with time.  At least from the end of the 18th century, the placebo effect was recognized as medical phenomenon when a fake treatment produces real results.

After World War II, with the advent of randomized, controlled trials, scientists began to notice that a high percentage of people given a fake treatment showed significant improvement.

What causes the placebo effect?

It is believed that two main causes of the placebo effect are conditioning and expectation.

Conditioning is a concept made famous by Pavlov in his studies of dogs.  He noticed that dogs would salivate upon seeing food.  Pavlov was able, by ringing a bell when serving food, to train dogs to eventually start salivating upon hearing a bell alone.

This is a trained response.  The theory of conditioning in placebo effect is that similarly, we are trained to respond in a certain way to being given a pill and seeing a doctor/being in a medical setting.

Just like the bell can cause a dog to salivate, a pill or other treatment can cause us – at least in theory – to have a variety of responses, such as feeling less depressed or less pain or having a better heart rate.

The other cause, expectation, focuses on the powerful effect that expectations can have.  We naturally expect a treatment to have benefit.  This can translate into a sham treatment having real benefits.

For instance, take the case that a cream is rubbed on a painful spot.  If you are told that the cream will reduce pain, and so expect it, you are more likely to report pain reduction than someone who is not told that.

What is the placebo effect?

Research has shown that the placebo effect is not simply just psychological.  Rather, a placebo treatment can produce a variety of specific, measurable biochemical differences.

Studies have shown that a placebo for depression can cause changes in electrical and metabolic behavior in the brain.  A placebo for a heart condition can affect the beta-adrenergic hormonal system, and one for an immune condition can alter interleukins and interferon among others.

Proving that placebos have real, physical effects is the ability to block the placebo effect with medication.

Administration of naloxone, in particular, which is used to treat addictions, can prevent and reverse the pain-blocking effects of a placebo.

In summary

The placebo effect remains a mystery because it simply doesn’t make sense that a fake treatment can have real health benefits.  That said, we now know that it has real biochemical effects that can be measured and even blocked.

A better understanding of this phenomenon could lead to improved healthcare in a variety of ways.


  1. Well, the placebo effcet has to be measured against something and it’s effcetiveness can only be measured that far. In pharmaceutical trials the placebo is the control, the standard by which the effcetiveness of the drug is measured. You should have three groups: one testing a thing (for lack of a better term), one with the placebo (that they think is the thing), and one group without any influence other than testing as the final control. Without the setting of a proper clinical trial, you might also have to rely on self-reporting. Make sure to note this in your findings.My first thought is a sports drink. Have three groups where all the members are of equal physical fitness and do not drink sports drinks (regularly). Give one group the drink, one group Kool-aid in the drink bottles (since they all taste like Kool-aid anyway), and the last group nothing. Monitor some sort of physical activity, like the amount of distance run everyday and how the subjects feel after their activity, whether they’re more tired, able to run more, etc.Another thought is a study aid. You couldn’t use an actual pharmaceutical for this, dispensing Ritalin, but you could still have a placebo and control group. Over a certain period, monitor the study habits of two groups, one with generic aspirin that you claim is a study aid and the other a control, and have each group self-report on changes to their habits.

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