When it’s quiet time for the mind
During the last decade, there has been a growing body of research showing that regular meditation -- the practice of quieting the mind through deep, continued thought -- can help reverse some of the ill effects of stress. Studies have shown that regular practice of meditation can lower blood pressure, heart rate and respiration, reduce anxiety and anger, and help alleviate insomnia and mild to moderate depression, as well as lead to other benefits.
Many doctors and researchers have speculated about the reasons meditation -- sometimes called the “relaxation response” -- produces these effects. But a credible scientific explanation has been elusive until now. Such an explanation could describe how changes in brain function produced by altering one’s mental focus affect people’s moods and metabolism.
A new study by researchers at the University of Wisconsin and the University of Massachusetts is likely to provide a significant first step to answering the question of 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, founding director of the Stress Reduction Clinic and Center for Mindfulness at the University of Massachusetts Medical School. It has been accepted for publication in Psychosomatic Medicine, a peer-reviewed journal, according to the researchers.
The researchers sought to test a particular theory: that in people who are stressed, anxious or depressed, the right frontal cortex of the brain is often overactive and the left frontal cortex, relatively underactive. Many such people also show heightened activation of the amygdala, a key brain center for processing fear.
By contrast, people who are usually calm and happy typically show greater activity in the left frontal cortex, relative to the right. These folks also pump out less of the stress hormone cortisol, recover faster from negative events and have higher levels of natural killer cells, a type of white blood cell that battles infection and is a measure of immune system function.
Each person, notes Davidson, tends to have 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 may do, the researchers reasoned, is nudge this balance in a favorable direction.
To find out, they recruited stressed-out volunteers from Promega Corp., a large high-technology firm in Madison, Wisc. The volunteers underwent EEGs (electro-encephalographs), in which electrodes were placed on the scalp to collect brain-wave information. The volunteers were then randomly divided into two groups: 25 were placed in the meditation group and 16 into the control group, which received no meditation training.
The meditators took an eight-week course in which they received 2 1/2 hours a week of meditation training at their workplace. During the sixth week, they had an all-day, silent meditation retreat. At the end of the eight weeks, both meditators and controls were again given EEG tests and a flu shot. All also got 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 non-meditators’ brains did not, suggesting that regular meditation may have shifted the “set point” to the left, said Kabat-Zinn. He said the findings were significant because the subjects were novice meditators, not people with many years of meditation training and practice.
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 meshes well with findings of a smaller study published in May 2000 by Sara Lazar, a neurobiologist at Massachusetts General Hospital, Dr. Herbert Benson of Harvard University and others. That study looked at five highly trained Sikh meditators and, using a brain-scanning technique called functional MRI, showed that blood flow in the brain shifts depending on whether the meditators where truly meditating or simply reciting words like “dog” and “cat” to themselves.
It also fits with research suggesting that certain drugs produce meditation-like effects on the brain, says Dr. Solomon Snyder, a neuroscientist at Johns Hopkins Medical School in Baltimore. Snyder says meditation may increase the amount of serotonin, a calming neurotransmitter, in the brain.
Among those fascinated with this research is the Dalai Lama, the leader in exile of Tibetan Buddhism, who has visited Davidson’s lab. One of his goals, according to those who know him, is to see whether scientists can explain objectively the subtleties of the mind that Buddhists have long understood subjectively.
A few small studies on several dozen novice and experience meditators won’t provide a final answer on how meditation effects brain function and health, and some experts caution about expecting too much from research in this area.
Meditation is “a wonderful tool,” but no one should expect meditation to work miracles, cautions Barrie Cassileth, chief of the integrative medicine service at Memorial Sloan-Kettering Cancer Center in New York City. It “cannot bring about levitation. It cannot control cellular activity in the sense of getting rid of disease.”
But these early studies do suggest that the subtleties of mind long known subjectively to proficient meditators may prove capable of being understood objectively as well.
