Most of us assume that, when it comes to resisting infectious diseases, are pretty fatalistic. In the absence of a vaccine, we may try whatever currently popular substance is supposed to “boost our immune system,” but we figure that’s about all we can do.
Yet, there has always been tantalizing evidence that some people seem to remain healthier than others just through the power of positive thought. That’s always puzzled scientists, because they didn’t know of any mechanism to account for it. That may have just changed, however.
Last week, biologist Marian Cleeves Diamond, 73, presented new research at a meeting of the Society for Neuroscience at the University of California in Berkeley that indicates that people who play contract bridge have more immune cells after the game than they did before.
Diamond has been studying the connection between the brain and the immune system for more than 15 years. Her interest is based on family tragedy: when Diamond was 19, her sister died of systemic lupus erythematosus, a disease in which the immune system attacks the body’s own tissues.
Diamond’s first step was comparing the brains of normal mice with “nude mice,” mice bred to have a deficient immune system. The only measurable difference was in the thickness of the dorsolateral cortex, part of the outer layer of the brain that is involved in working memory, planning ahead and initiative. In nude mice, it was thinner.
Nude mice have deficient immune systems because they have deficient thymus glands. The thymus gland produces special white blood cells called T cells. T cells perform several vital functions. Some, called “helper” cells, control the white blood cells that swallow bacteria and the B cells that produce antibodies. Other T cells dampen the immune response when it is no longer needed, and still others destroy the body’s own cells that have been infected.
In the early 1990s Diamond and her colleagues transplanted normal thymus glands into nude mice. All of the mice developed normal levels of T cells–and showed a thickening of the dorsolateral cortex.
Diamond began trying to figure out a way to see if the same link between the dorsolateral cortex and the immune system exists in humans. In her research, she came across a 1990 paper by a team of researchers from the National Institute of Mental Health, who found, using a PET scanner, that the human dorsolateral cortex is stimulated by a complex card sorting task often used for psychiatric analysis.
That gave Diamond the idea of testing the connection between the dorsolateral cortex and the immune system by using a similar mental task involving cards–namely, contract bridge.
“It is the closest activity to a challenging card sorting task that also contains multiple factors that should stimulate the dorsolateral cortex,” she said. “Bridge players plan ahead, they use working memory, they deal with sequencing, initiation and numerous other higher-order functions with which the dorsolateral cortex is involved.”
Finding test subjects proved to be easy: her old college roommate, Marian Everett, is a member of a golfing and bridge club in Orinda, California. In no time at all Diamond had 12 volunteers, all women in their 70s and 80s. (She preferred women as subjects because most of the mice she worked with were also female.)
The women were divided into three foursomes, each of which played played a one-and-a-half-hour bridge set. Blood samples were taken before and after, and the number of T cells counted.
It turned out that the number of helper T-cells, the ones that direct the work of other white blood cells and antibody-producing B cells, increased significantly in two of the groups. (In the third group, the increase was not considered significant.)
The next step, Diamond suggests, is to use a nuclear magnetic resonance machine to see if the dorsolateral cortex really does show greater activity during bridge playing.
Obviously this is a very small study, but it does show for the first time that brain activity can affect the immune system–which leads to the intriguing possibility that humans might be able to learn how to voluntarily control their white blood cell count to help combat illness.
So maybe you should break out a deck of cards instead of echinacea when you feel that tickle in the back of your throat that tells you you have a cold coming on.
It appears contract bridge, not laughter, is actually the best medicine.
