"Our results suggest that meditation can produce experience-based structural alterations in the brain," says Sara Lazar, PhD, of the MGH Psychiatric Neuroimaging Research Program, the study's lead author. "We also found evidence that meditation may slow down the aging-related atrophy of certain areas of the brain."

Studies have shown that meditation can produce alterations in brain activity, and meditation practitioners have described changes in mental function that last long after actual meditation ceases, implying long-term effects. However, those studies usually examined Buddhist monks who practiced meditation as a central focus of their lives.

To investigate whether meditation as typically practiced in the U.S. could change the brain's structure, the current study enrolled 20 practitioners of Buddhist Insight meditation - which focuses on "mindfulness," a specific, nonjudgmental awareness of sensations, feelings and state of mind. They averaged nine years of meditation experience and practiced about six hours per week. For comparison, 15 people with no experience of meditation or yoga were enrolled as controls.

Using standard MRI to produce detailed images of the structure of participants' brains, the researchers found that regions involved in the mental activities that characterize Insight meditation were thicker in the meditators than in the controls, the first evidence that alterations in brain structure may be associated with meditation. They also found that, in an area associated with the integration of emotional and cognitive processes, differences in cortical thickness were more pronounced in older participants, suggesting that meditation could reduce the thinning of the cortex that typically occurs with aging.

"The area where we see these differences is involved in both the modulation of functions like heart rate and breathing and also the integration of emotion with thought and reward-based decision making - a central switchboard of the brain," says Lazar. An instructor in Psychology at Harvard Medical School, she also stresses that the results of such a small study need to be validated by larger, longer-term studies.