Power of Positive Thought

Scientists have identified how positive thinking can help boost the immune system...

A positive state of mind is generally associated with better physical well being, but exactly how activation of the reward system (the region of the brain activated by positive emotions) can promote a healthy body has remained unknown.

Now, writing in Nature Medicine, researchers from The Technion-Israel Institute of Technology have stimulated this region in the brains of mice to show how the feel-good factor can manipulate the immune system.

One day after the reward system was stimulated, the mice were exposed to E. coli bacteria.  Following the stimulation, the immune system was more effective at fighting the bacteria.  This enhanced immune response was still observable 30 days after the stimulation event, indicating the stimulation strengthened the animals' immunological memories of the bacteria.  

These findings suggest there is a connection between the reward system of the brain and the immune system.  "The tricky part is to be able to understand what goes in between," explains Dr Asya Rolls, who lead the study.

They believe that part of the answer may lie in the sympathetic nervous system - one of the nerve pathways of the body.  The brain controls the activity of this system, and it reaches all organs of the body, including the immune organs.

By chemically switching off the sympathetic nervous system, the team found that stimulating the reward system then had no effect on the immune system.  "It indicated that the sympathetic nervous system is involved in mediating the connection from the reward system to the immune response."

Rolls also believes this effect may have evolutionary benefit.  The reward system is activated under natural conditions like feeding and sex, which are also situations where we are exposed to a lot of bacteria.  It therefore makes sense for there to be this connection.

This artificial stimulation of the reward system is likely to be more intense than when the system is naturally stimulated, however the results have uncovered the potential of the reward system to affect immunity.

"Only if we understand the mechanisms of how the brain can impact physical well being, can we use it for our benefit."