Another example of the placebo effect

In a previous post I gave an example of the placebo effect, which is defined as the positive (or negative) effect on a patient caused by the belief that the patient is receiving beneficial (or harmful) treatment (i.e. power of positive thinking, Figure 1). In the previous example, the medical condition was hot flashes and their frequency in menopausal women dropped by 52% in patients receiving a placebo, which was not much lower than women taking a herbal medicine (frequency was reduced 62%).

This week a study was published (and reported by NPR) that examined migraine headaches in patients who received either a drug (Maxalt) that reduces migraine attacks or a placebo. The experimental protocol was as follows:

"The researchers asked all of their subjects to refrain from taking any medication for two hours after the onset of their first migraine. Then they were given six envelopes, each containing a pill to be taken during their next six migraine attacks. Subjects rated their amount of pain two hours after taking each pill."

The six possibilities were placebo labeled as (1) placebo, (2) Maxalt or placebo, and (3) Maxalt, and Maxalt labeled as (4) placebo, (5) Maxalt or placebo, and (6) Maxalt.

Interestingly patients given placebo labeled as placebo felt 26% less plain than no treatment. With placebo labeled as Maxalt, they felt 40% less pain. Surprisingly Maxalt labeled as placebo gave a similar efficacy as placebo labeled as Maxalt.

The authors concluded that "relative to no treatment, the placebo ... accounted for more than 50% of the drug effect." An amazing finding.

There are limits to the placebo effect, however:

"When the researchers asked patients if they were totally pain-free 2 1/2 hours after taking the pills, patients said Maxalt was almost four times better — 25.5 percent versus 6.6 percent."

This is interesting because describing the amount of pain is somewhat subjective whereas describing the presence or absence of pain is more objective. Thus the placebo effect may be greater in subjective evaluations (by the patient) of medical effect compared to more objective evaluations.

Nevertheless an important point made at the end of the article is that doctors can help patients by not only prescribing the best medicine, but also by encouraging patients to believe that the medicine will help them:

"Whether treatment involves medication or placebo, the information provided to patients and the ritual of pill taking are important components of care."

Figure 1. A positive mind-set can aid in the curative process.