From an article by Michael Haederle on The Buddhist Channel:
Scientists using scanning technology are finding that regular meditation has a measurable effect on a variety of brain structures related to attention — an example of what is known as neuroplasticity, where the brain physically changes in response to an intentional exercise.
A team of Emory University scientists reported in early September that experienced Zen meditators were much better than control subjects at dropping extraneous thoughts and returning to the breath. The same researchers reported last year that long-time meditators don’t lose gray matter in their brains with age the way most people do, suggesting that meditation may have a neuro-protective effect.
Other studies have found that practitioners of insight meditation have noticeably thicker tissue in the prefrontal cortex (the region responsible for attention and control), and that experienced Tibetan monks practicing compassion meditation generate unusually strong and coherent gamma waves in their brains.
“There are a lot of potential applications for this,” said Milos Cekic, a member of the Emory team. He suspects the simple practice of focusing attention on the breath could help patients suffering from depression, anxiety, post-traumatic stress and other conditions characterized by excessive rumination.
Meanwhile, a meditation-derived program developed at the University of Massachusetts called Mindfulness Based Stress Reduction (MBSR) is gaining popularity for treatment of anxiety and chronic illnesses at medical centers around the U.S.