Does a placebo still work if you know it is a placebo?

Chronic low back pain is an extremely common problem for individuals worldwide, leading to frequent feelings of disability. There are many pharmaceutical drugs patient’s use for chronic low back pain, but their effectiveness seems to be limited at times. Interestingly enough, recent research has shown that placebo treatments may have utility in managing chronic low back pain. Carvalho and colleagues recently published a study in Pain that aimed to examine patient outcomes using treatment as usual (TAU) and TAU with the addition of placebo pills. The study included participants 18 years or older that have had persistent low back pain for over 3 months. Participants were randomly put into 2 groups – an experimental group and a control group that would resume treatment as usual with the option of taking placebo pills at the end of the study. All participants were educated on what a placebo pill is, and the possible effects it can have on their body.  The experimental group took 2 pills twice a day for 3 weeks. Patients rated their pain on a Numeric Pain Rating scale from 0 (no pain) to 10 (worst pain imaginable) before the start of the treatment, midway and at the end. Measurements for maximum, minimum, and usual pain were recorded. In addition to measuring pain, participants filled out the Rolland-Morris Disability Questionnaire to give researchers an idea of what difficulties they were having on a daily basis with a higher score indicating a higher level of disability.

Given that the participants were fully aware of the placebo pills, you would expect that the treatment would not be as effective. Interesting enough, this study showed just the opposite. Overall, the placebo group reported greater pain reduction on each of the 3 pain rating scales as well as a decrease in pain-related disability compared to treatment as usual. Even the participants that voluntarily took placebo pills following treatment as usual experienced significant pain relief and decreases in pain-related disability. In fact, 17 participants requested a prescription for these placebo pills to treat their chronic low back pain at the end of the study! The mind is a powerful thing!