Doctors have long known that stress and negative emotions can endanger your health, but they've had little idea of how the brain mediates this effect. A new study strengthens the link between emotions and the immune system.
A team led by University of Wisconsin psychology graduate student Melissa Rosenkranz played with the emotions of 52 adults just before they were given a flu shot. Subjects were asked to think and write about both extremely happy and extremely bad emotional experiences, while the researchers monitored their brain activity using electroencephalography. Six months later, the subjects returned and the scientists drew blood and measured the levels of antibodies against the flu virus.
Previous research has shown that activity in the right frontal lobe is associated with negative emotions. Activity in the left frontal lobe, on the other hand, is associated with positive emotions. In the current study, subjects who had the most negative emotional responses, as determined by high activity in the right prefrontal lobe, had fewer antibodies--a sign of a weakened immune response, the team reports online this week in the Proceedings of the National Academy of Sciences. "There's been a lot of work showing that stressful life events may produce some impairment in immunity but the brain has been left out of the equation," says senior author Richard Davidson. He predicts that prefrontal lobe activity will turn out to be a key part of that brain circuitry.
Janice Kiecolt-Glaser of Ohio State University in Columbus has done research showing that the stress of taking care of a spouse with Alzheimer's makes people more vulnerable to getting the flu. This study, she says, "gives us good biological links" between a person's emotional state and their health.