In the past decade, researchers have been using modern technology to study how meditation affects the structure of the brain. They have found that between controls and meditators, there are differences in both gray matter (tissue containing neuronal cell bodies) and white matter (the connective tissue between regions of the brain).
While brain research is still a young field of study, these findings are important because they illustrate the brain’s plasticity and indicate that we may be able to prevent declines in brain function that were previously thought to be an inevitable part of aging.
Gray matter. Compared with controls, people who meditate regularly have more gray matter in parts of the brain that are responsible for attention and for awareness of subjective internal states. Scientists discovered that experienced mindfulness meditators had more cortical thickness in the prefrontal cortex, especially in the right anterior insula—regions associated with attention, inner awareness and sensory processing (Lazar et al. 2005). Zen experts were found to have a thicker anterior cingulate cortex, a brain region related to pain sensitivity (Grant et al. 2010).
In a study conducted at Massachusetts General Hospital in Charlestown, Massachusetts, researchers found that participation in a Mindfulness-Based Stress Reduction for 8 weeks was associated with increases in gray-matter density of the brain in areas involved in learning and memory, emotion regulation, self-referential processing, and the ability to gain perspective (Holzel et al. 2010).
Lead study author Britta K. Holzel, PhD, noted that while it may be possible for new brain cells to develop, a change in existing cells seemed the more likely explanation for the improvements. She said, “It could even be a change in the supporting tissue (glia) and not in the neurons. Hopefully, future research will give us a better understanding of it.”
White matter. New research suggests that meditation training not only results in denser gray matter in different brain regions; it also leads to more white matter—an effect that improves the efficiency with which parts of the brain communicate with each other. Researchers from the University of California, Los Angeles, found evidence to suggest that people who meditate have stronger connections between brain regions (Luders et al. 2011).
“Our results suggest that long-term meditators have white-matter fibers that are either more numerous, more dense or more insulated throughout the brain,” said Luders. “We also found that the normal age-related decline of white-matter tissue is considerably reduced in active meditation practitioners.”
Scientists at the University of Oregon in Eugene identified changes in the structural efficiency of white matter in the brain as a result of participation in integrative body-mind training, a method of meditation adapted from traditional Chinese medicine (Tang et al. 2012). In this study, after 1 month or only 11 hours of practice, the brains of novice meditators showed increases in both axon density and myelin formation. Study authors concluded that “this dynamic pattern of white matter change involving the [anterior cingulate cortex], a part of the brain network related to self-regulation, could provide a means for intervention to improve or prevent mental disorders.”
Researchers have not yet identified the mechanisms to explain why meditators have more brain tissue. Luders said, “It is possible that meditators might have brains that are fundamentally different to begin with. For example, a particular brain anatomy may have drawn an individual to meditation or helped maintain an ongoing practice—meaning that the enhanced fiber connectivity in meditators constitutes a predisposition towards meditation, rather than being the consequence of the practice.”
More research is needed, especially longitudinal studies to explore causal mechanisms and to distinguish the relative contributions of genetics from the impact of meditation practice.