FOR DECADES, open-minded Westerners - patients and doctors alike - have been touting the medical benefits of meditation.
It has been shown to lower blood pressure, heart rate and respiration; to reduce anxiety, anger, hostility and mild to moderate depression; to help alleviate insomnia, premenstrual syndrome, hot flashes and infertility; and to relieve some types of pain, most notably tension headaches.
What nobody has come close to explaining is how meditation might work. That is, what mechanisms within the brain might explain why changing one's mental focus can have such large effects on mood and metabolism. Nor has there been much collaboration between experts in meditation such as Buddhist monks and neuroscientists.
All that is changing - fast.
A new study, accepted for publication soon in Psychosomatic Medicine, is a significant first step in understanding what goes on in the brain during meditation. The study was led by Richard Davidson, director of the laboratory for affective neuroscience at the University of Wisconsin, and Jon Kabat-Zinn, founder of the Center for Mindfulness at the University of Massachusetts Medical School.
The underlying theory is that in people who are stressed, anxious or depressed, the right frontal cortex of the brain is overactive and the left frontal cortex, underactive. Such people also show heightened activation of the amygdala, a key center for processing fear.
By contrast, people who are habitually calm and happy typically show greater activity in the left frontal cortex relative to the right. These lucky folks pump out less of the stress hormone cortisol, recover faster from negative events and have higher levels of natural killer cells, a measure of immune system function.
Each person has a natural "set point," a baseline frontal cortex activity level that is characteristically tipped left or right, and around which daily fluctuations of mood swirl. What meditation might do is nudge this balance in the favorable direction.
To find out, researchers recruited stressed-out volunteers from a high-tech firm in Madison, Wis. At the outset, all volunteers were tested with EEGs to collect brain-wave information. The volunteers were then randomly placed in a meditation group or a control group.
One group took an eight-week meditation course. Then, meditators and control-group members were again given EEG tests and flu shots. They also underwent blood tests to check for antibody response to the flu shots. Four months later, all got EEG tests again.
By the end of the study, the meditators' brains showed a pronounced shift toward the left frontal lobe, while the nonmeditators' brains did not, suggesting that meditation might have shifted the "set point" to the left. (The nonmeditators actually got slightly worse, perhaps because they were cranky from making several trips to the lab without the payoff of learning to meditate.) The meditators also had more robust responses to the flu shots. Indeed, the bigger the mood effect, the bigger the immune response.
The Wisconsin study fits with a smaller study published in May 2000 that looked at five Sikh meditators through a brain-scanning technique called functional MRI. It found a shift in blood flow in the brain during meditation.
The new meditation work also jibes with data suggesting certain drugs produce meditation-like effects on the brain, says Dr. Solomon Snyder, director of the department of neuroscience at Johns Hopkins School of Medicine. "It's reasonable to assume," he says, that meditation might increase serotonin, a calming neurotransmitter, in the brain.
Judy Foreman is lecturer on medicine at Harvard Medical School and an affiliated scholar at the Women's Studies Research Center at Brandeis University. Her column appears every other week. Past columns are available on www.myhealthsense.com.