There have been a number of studies documenting the effect of meditation on the brain, enough so that the claim that “meditation rewires your brain” is one that we see repeated lots of times. (I talk about it in The Distraction Addiction, and I suppose I’m going to need to talk about it in the new book as well.) Now, the Harvard Gazette reports that "a team led by Harvard-affiliated researchers at Massachusetts General Hospital (MGH)… [have been able] to document meditation-produced changes over time in the brain’s gray matter."
“Although the practice of meditation is associated with a sense of peacefulness and physical relaxation, practitioners have long claimed that meditation also provides cognitive and psychological benefits that persist throughout the day,” says study senior author Sara Lazar of the MGH Psychiatric Neuroimaging Research Program and a Harvard Medical School instructor in psychology. “This study demonstrates that changes in brain structure may underlie some of these reported improvements and that people are not just feeling better because they are spending time relaxing.”
In this study, they looked at 16 people who participated in the eight week-long Mindfulness-Based Stress Reduction (MBSR) program. Each person had an MRI two weeks before and after the program, and they spent about half an hour each day meditating. The team also conducted MRIs on a control group.
The analysis of MR images, which focused on areas where meditation-associated differences were seen in earlier studies, found increased gray-matter density in the hippocampus, known to be important for learning and memory, and in structures associated with self-awareness, compassion, and introspection.
Participant-reported reductions in stress also were correlated with decreased gray-matter density in the amygdala, which is known to play an important role in anxiety and stress. Although no change was seen in a self-awareness-associated structure called the insula, which had been identified in earlier studies, the authors suggest that longer-term meditation practice might be needed to produce changes in that area. None of these changes were seen in the control group, indicating that they had not resulted merely from the passage of time.
So what’s new about these findings?
Previous studies from Lazar’s group and others found structural differences between the brains of experienced meditation practitioners and individuals with no history of meditation, observing thickening of the cerebral cortex in areas associated with attention and emotional integration. But those investigations could not document that those differences were actually produced by meditation.