This opens the potential to create drugs that harness the brain’s ability to cure.
The placebo effect has perplexed scientists for years, and exactly how positive expectations can bring about actual changes in the body’s physiology still remains a mystery. However, new findings reported in Nature Medicine shed light on the phenomenon by showing that the brain’s reward center can give the body’s immune system a boost.
Researchers at the Technion-Israel Institute of Technology bred mice with designer receptors in the ventral tegmental area (VTA), which is a key brain region involved in the reward system. This allowed the scientists to easily stimulate the reward centers in the mice and then observe what changes would follow.
"Our findings indicate that activation of areas of the brain associated with positive expectations can affect how the body copes with diseases," senior author Asya Rolls, an assistant professor at the Technion-Israel Institute of Technology's Faculty of Medicine, said in a press statement.
In one experiment, the researchers injected mice with E. coli, and found that the VTA-activated mice could fight off the infection better than the control mice. By stimulating the brain’s reward system, the researchers saw an increase in the number of receptors on certain white blood cells in the mouse spleens, suggesting that the capacity to stave off infections had become enhanced.
In a second test, the scientists incubated immune cells from the VTA-activated mice exposed to E. coli, and they observed similar results in petri dishes as they did with the live mice. Compared to the ordinary immune cells, the VTA-activated ones were at least twice as effective at killing the E. coli bacteria.
Plus, this enhanced immune response appears to be lasting. Even a week after the mice were injected with E. coli, the VTA-activated rodents contained 86 percent more E.coli-specific antibodies in their blood serum, according to the researchers.
“Thus, our findings establish a causal relationship between the activity of the VTA and the immune response to bacterial infection,” the researchers write in Nature Medicine.
Going forward, the researchers hope to use these findings to harness the potential of the brain’s reward system to create “new therapeutic targets” that may “one day lead to the development of new drugs that utilise the brain's potential to cure," Rolls said in the release.