Neuroscientist Sara Lazar found that people who practiced meditation had more gray matter in the part of the brain linked to decision-making and working memory: the frontal cortex.
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While most people see their cortexes shrink as they age, 50-year-old meditators in the study had the same amount of gray matter as those half their age.
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Participants in the study averaged about 27 minutes of the habit a day, but other studies suggest that you can see significant positive changes in just 15 minutes a day.