A study on placebo pills in chronic pain treatment examined what factors might predict which patients will experience a beneficial “placebo effect”.
A placebo is an inactive substance given to patients that are not intended to have any effect on their medical condition. Placebos are sometimes used in trials of new treatments to compare the effects of the new drug relative to an inactive substance. Some patients experience positive physical effects after taking a placebo; this is known as a “placebo effect”.
It is not clear how the placebo effect happens, but some research suggests it may be linked to psychological and neurobiological interactions. Understanding more about placebo effects could help with the design and interpretation of new drug trials, or even provide alternative treatment options for some patients.
Researchers at the Northwestern University in Chicago, United States studied the effects of placebo pills in chronic pain treatment and looked at what factors might predict which patients will experience a beneficial placebo effect. They recently published their findings in Nature Communications.
The researchers analyzed 63 patients with chronic back pain in an eight-week study. After an initial assessment, they randomly allocated 43 patients to receive placebo pills and 20 patients to the “no treatment” or “control group”. All patients kept daily records of their pain on a smart-phone app. The participants all attended the study center four times to have brain scans examining several brain structures. At these visits, they also completed a series of detailed questionnaires assessing various psychological factors and their pain characteristics.
Patients receiving placebo pills had greater pain reduction than the control group
The daily pain records showed that overall patients receiving placebo pills had a greater pain reduction compared to patients in the no treatment group. This indicated that the placebo pills induced pain relief. Within the placebo group, the researchers identified “responders” (24 patients) who showed a greater placebo effect, and “non-responders” (19 patients).
Further analysis of the brain scans and psychological questionnaires suggested that “responders” had different brain anatomy and psychological traits to “non-responders”. The responders had a thicker cortical sensory area and prefrontal functional pathways in the brain. In the psychological assessments, responders were more open to new experiences, emotionally self-aware, sensitive to painful situations and mindful of their environment. These factors may help predict which patients will experience a beneficial placebo effect.
Some chronic pain patients may benefit from placebo therapy
This study offers some insight into the complex mechanisms underlying placebo effects. Although these are preliminary findings, the researchers suggest that doctors treating patients with chronic pain should consider whether some might benefit from placebo therapy. Personality and psychological questionnaires may be a simple method of predicting which patients will be placebo responders. Placebo therapies would be cheaper and without the side effects that can accompany active drugs.
Written by Julie McShane, Medical Writer
- Vachon-Presseau E, Berger SE, Abdullah TB, et al. Brain and psychological determinants of placebo pill response in chronic pain patients. Nature Communications DOI:10.1038/s41467-018-5859-1.
- EurekAlert. Sugar pills relieve pain for chronic pain patients. 12 Sept 2018. https://www.eurekalert.org/pub_releases/2018-09/nu-spr091218.php