Many of us have probably heard about placebo treatments and their deceiving effects on patients. While placebos do not have active properties, they may still have the power to alleviate something like pain, for example. An estimated one-third of people who take placebos will report an end to their symptoms if they believe the cause of that relief to be the medication. Some may believe that a patient’s illness must have been “imaginary” if they benefitted from a placebo drug.
However, recent research shows otherwise. By changing an individual’s mindset and beliefs, placebo treatments may actually help create some changes in the brain as well. This would explain the reduced symptoms. How does this happen? What is the scientific evidence to prove it? And what neural changes occur?
Most studies conducted to date have small samples and are therefore not enough to fully understand the neural mechanisms behind placebo effects. A recent study published in the Nature Communications journal conducted the first large-scale mega-analysis of these small-scale neuroimaging studies about placebo effects. Researchers Matthias Zunhammer, Tamas Spisak, Tor Wager, and Ulrike Bingel analyzed 20 fMRI studies with over 600 healthy participants who were all tested for their brain’s pain-related activity after taking a placebo treatment.
Participants who reported feeling less pain across the studies were found to actually show signs of this in their brain activity. Researchers noted the analgesia (inability to feel pain) a participant reported along with their fMRI brain scans. They found negative correlations for several brain areas; the less brain activity, the more analgesia a participant reported.
The thalamus, which is a gateway for all sensory motor input to the brain, was the area most strongly affected by placebo treatments. The posterior insula in the brain’s pain pathway also showed decreased activity with placebo treatments. The basal ganglia, which is vital for motivation and connecting experiences to actions, was affected as well. Therefore, the placebo may actually be affecting the brain’s pain construction pathway and “changing the circuitry that’s important for motivation,” as the lead researcher, Wager, said.
The prefrontal cortex, however, varied the most in its activity across studies. No certain areas were found to be associated with pain-related placebo effects. This may be explained by the different effects of unique thoughts and mindsets that each participant had. For instance, “other work in Wager’s laboratory has found that rethinking pain by using imagery and storytelling typically activates the prefrontal cortex, but mindful acceptance does not.” This suggests that placebo effects on the prefrontal cortex vary from person to person, depending on their thinking and attitude.
Overall, researchers concluded that “placebo treatments affect pain-related activity in multiple brain areas, which may reflect changes in perception and/or other affective and decision-making processes surrounding pain.” This suggests that something as simple as changing one’s mindsets/beliefs can have enough power to reduce feelings of pain as a direct result of reducing brain activity. These findings have several implications for patient care, drug-development, and research in neuroscience.
The regions of the brain that showed the least activity and correlated strongly with the participants’ analgesia could be studied further to assess pain pathways in the brain. Additionally, placebo treatments may be considered as an option to enhance the recovery of some patients and reduce their reliance on pain medication.