Nov. 23, 2000 Next time you feel a little under the weather, try a novel way to boost your immune system - play contract bridge.
In a presentation at this week's meeting of the Society for Neuroscience, University of California, Berkeley, biologist Marian Cleeves Diamond will describe an experiment showing that contract bridge players have increased numbers of immune cells after a game of bridge.
Based on her previous work, and that of others, Diamond interprets the findings as strong evidence that an area of the brain involved in playing bridge stimulates the immune system, in particular the thymus gland that produces white blood cells called T cells, or T lymphocytes.
If her study is borne out, this would be the first time a specific area of the cortex - in this case, part of the frontal lobe of the brain - has been linked with the immune system.
"People are aware that voluntary activities like positive thinking and prayer work to keep us healthy, but no one has had a mechanism," said Diamond, a professor of integrative biology in the College of Letters & Science at UC Berkeley. "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."
A poster describing the study will be displayed Wednesday, Nov. 8, during the Nov. 4-9 meeting in New Orleans of the Society for Neuroscience.
The experiment is the culmination of more than 15 years of work on rat and mouse brains by Diamond and her colleagues in search of a cortical area connected to the immune system. It's also a poignant tribute to her sister, who died when Diamond was 19 of the autoimmune disease systemic lupus erythematosus.
"Someday, I thought, I will find something that correlates with what killed her," said Diamond, 73. "But I'm a neuroscientist, not an immunologist, so I had to touch the immune system through the brain."
Diamond chose to study bridge players from an Orinda, Calif., women's bridge club because bridge is a game likely to stimulate an area of the brain - the dorsolateral cortex - that she suspected influences the immune system. She selected women as subjects because most of her laboratory experiments have involved immune compromised female mice.
Diamond and graduate student Jean Weidner 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. Weidner, a former phlebotomist, drew blood samples before and after the sets, and delivered them to immunology research associates Peter Schow and Stan Grell to measure the numbers of immune cells.
Only the levels of CD-4 positive T cells changed in the 12 subjects. In two of the groups, levels increased significantly. In the third group, T cell levels increased only slightly, not enough to be statistically significant.
T cells are white blood cells produced by the thymus gland and sent out to patrol the body in search of viruses and other invaders. T cells that sport a surface marker called CD-4 are "helper" cells that regulate the activity of antibody-producing B cells and of other T cells.
In 1985, Diamond and her students first focused on the dorsolateral cortex - a brain area behind the forehead and a little to the side - after comparing the brains of normal mice with immune deficient mice, called nude mice. The only brain difference they could measure was in the dorsolateral cortex, which was thinner in nude mice on both the right and left sides of the brain. The cortex, the outer layer of the brain, deals with higher order functions; the dorsolateral cortex is involved with such things as working memory, planning ahead and initiative.
Because nude mice have deficiencies in their thymus gland, in the early 1990s Diamond and then doctoral student Gary Gaufo, who has since obtained his PhD, transplanted normal mouse thymus glands into immune compromised mice. Surprisingly, all of the mice developed normal levels of T cells and also showed thickening of the dorsolateral cortex.
Given the apparent connection between the thymus gland - the source of T cells - and the dorsolateral cortex, she looked around for a way to test the connection in humans. She discovered a 1990 paper by a team of researchers from the National Institute of Mental Health reporting that the dorsolateral cortex is stimulated by a card sorting task used for psychiatric analysis. The authors had used a PET scanner to determine the parts of the brain that were active during the task, comparing schizophrenics with normal subjects.
While that task, the so-called Wisconsin Card Sorting Task, is suitable for psychiatric tests, she decided that contract bridge would be a perfect substitute to use with normal subjects.
"Contract bridge was ideal for what we were after," she said. "It is the closest activity to a challenging card sorting task that also contains multiple factors that should stimulate the dorsolateral cortex. Bridge players plan ahead, they use working memory, they deal with sequencing, initiation and numerous other higher order functions with which the dorsolateal cortex is involved."
Luckily, her old college roommate, Marian Everett, was a member of a golfing and bridge club in Orinda, so Diamond approached her about finding a group of 12 players.
"They were so willing to be part of the experiment," Diamond said, that she had no problem getting enough volunteers.
In the future, as a possible follow-up study, Diamond suggests using a functional nuclear magnetic resonance machine to see if the dorsolateral cortex actually does show greater activity during bridge playing than during rest.
Because the brain's cortex is under voluntary control, she hopes her findings lead to ways to educate the brain to improve health.
"If we could find out how to regulate our immune system voluntarily through the brain's cortex, I would feel extremely happy," Diamond said.
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