Placebos have the potential to improve our moods. According to a study published online, mild electric shocks to the brain can amplify the effect in the journal Proceedings of the National Academy of Sciences on May 3. The finding suggests that it may be possible to increase the predictive power of expectations to improve treatment outcomes.
According to Dr. Jian Kong, a pain researcher at Massachusetts General Hospital in Charlestown, this is the first study to demonstrate that altering brain activity enhances placebo and blunts pain-inducing nocebo effects.
The placebo effect occurs when an individual feels better following the administration of an inactive substance, such as a sugar pill because they anticipate that it will help. The nocebo effect is the placebo effect’s evil twin: an individual feels worse following the administration of an inactive substance for which they anticipate unpleasant side effects. To confound participants’ expectations, Kong’s team subjected them to excruciating heat. While participants were lying in a functional MRI scanner, the heat was applied to the forearm via a thermal stimulator. Each individual was given three creams, one for each arm. One cream was a numbing lidocaine cream, another was a regular cream, and the third was a pain-increasing capsaicin cream, participants were informed. However, each of the creams was actually the same colour-dyed inert lotion.
Participants reported decreased pain intensity due to the heat applied to the “lidocaine” patch of skin, which is consistent with a placebo effect. Additionally, individuals reported increased pain intensity when exposed to “capsaicin” skin, which is consistent with a nocebo effect.
Prior to testing the placebo and nocebo effects, researchers used a technique called transcranial direct current stimulation, or tDCS, to deliver electric currents to the brains of some participants. Two electrodes attached to the scalp had a weak electric current to the brain during these tDCS sessions, altering the behaviour of brain cells.
Definite participants received tDCS to the right dorsolateral prefrontal cortex, an area of the brain thought to be involved in placebo and nocebo effects. The researchers used two types of current: positive anodal tDCS, which typically increases nerve cell activity, and negative cathodal tDCS, which naturally decreases cell activity.
When the heat was applied to the skin with “lidocaine” cream, those who received cathodal tDCS reported more potent placebo effects compared to those who did not receive tDCS. The stimulation diminished the nocebo effect of the “capsaicin” cream in subjects who received anodal tDCS.
Brain stimulation altered neural pathways previously implicated in the placebo and nocebo effects. Cathodal transcranial direct current stimulation, for example, enhanced connections between the targeted brain area and a nearby area involved in emotion and cognition. According to Kong and colleagues, this strengthened pattern was associated with participants reporting a more substantial placebo effect.
Kong confirms. His study was small, and people react differently to pain and placebos. “However, I must say that this is also encouraging,” he adds.
Manipulating placebo analgesia and nocebo hyperalgesia by changing brain excitability Yiheng Tu, Georgia Wilson, Joan Camprodon, Darin D. Dougherty, Mark Vangel, Fabrizio Benedetti, Ted J. Kaptchuk, Randy L. Gollub, Jian Kong Proceedings of the National Academy of Sciences May 2021, 118 (19) e2101273118; DOI: 10.1073/pnas.2101273118
Main Image Credit: Mohamed Hassan