Want to stay healthy? Play bridge. A new study by a University of California-Berkeley researcher indicates that playing contract bridge leaves people with higher numbers of immune cells.
"People are aware that voluntary activities like positive thinking and prayer work to keep us healthy, but no one has had a mechanism," said Marian Cleeves Diamond, a professor of integrative biology at Berkeley.
Diamond's study, presented in New Orleans this week at a meeting of the Society for Neuroscience, could be the first evidence that the human cortex -- which is subject to voluntary control -- can play a role in stimulating the immune system.
"These data, though preliminary, show that brain activity affects the immune system, and support the possibility of us learning to voluntarily control the level of white blood cells to help combat disease and other illnesses," she said.
Diamond's study is founded on some 15 years of research into rat and mouse brains in which researchers have sought to identify a specific area of the cortex which might play a role in the body's immune response.
For the human element of the research, she selected players in women's bridge club in Orinda, California. Bridge was selected as the game because it was seen as likely to stimulate an area of the brain -- the dorsolateral cortex - which might influence the immune system.
"Contract bridge was ideal for what we were after," 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."
Diamond and her team divided the 12 women, all in their 70s and 80s, into three groups, and had each group play a one-and-a-half hour bridge set.
In blood samples taken both before and after the games, the subjects all revealed changes in the levels of CD-4 positive T cells, the white blood cells which patrol the body in search of viruses and other invaders.
Diamond said that in two of the groups, the levels of these T cells increased significantly. The third group showed only a slight increase, not enough to be statistically significant. The rise in the number of CD-4 cells was the only change visible in all of the blood tests.
Diamond cautioned that her findings were preliminary, and said that more research needed to be done to nail down the relationship between the cerebral cortex and the human immune system. But she added that, as preliminary findings go, these were both encouraging and exciting.
"Since we know the function of this particular area of the brain, through voluntary control we may perhaps learn to change our immune system positively," she said in an interview. "That's what is causing the excitement."