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Meditation and the Effects on Your Brain

March 21, 2017

Vinodh Chandra - Medical Student1, Matthew Vasey MD2


1MD Candidate, University of South Florida Morsani College of Medicine, Class of 2018
2Department of Emergency Medicine, Tampa General Hospital | TeamHealth, an affiliate of University of South Florida Morsani College of Medicine

Disclosure: Opinions reflect neither employer nor affiliated institutions, soley those of the author(s).


In the past decade, meditation has swept through our culture like wildfire. If you take a moment to google "meditation', you'll find countless apps, news articles, and blog posts touting its countless mental and physical benefits. From staving off stress, anxiety, and depression to curbing your ravenous, emotionally-driven appetite, meditation seems to be a wonder-drug (see "gulley stones"). We know meditation is a deep-rooted spiritual practice in Eastern religions. We're aware of Tibetan Monks who are supposedly the "happiest" people on Earth. And we've even heard of high-powered CEOs, visionaries, and entrepreneurs who attribute their daily practice as fundamental for their success. Yet, in light of the fact that the practice of meditation has weathered the test of dynamic times, cultures, and religions, it is still commonly met with skepticism. Perhaps something that is so practical, simple, and easy seems too-good-to-be-true. Or maybe it's the subjective nature of reports we hear about meditation that cause us to instinctively raise our brow. We in the West live in an evidence-driven, results minded culture. As such, the quality and quantity of meditation-based research has increased dramatically over the last decade, especially in the realm of understanding meditation's effect on the human brain. Let's take a closer look, and explore whether some of this research parallels what we've heard about meditation.

What Happens to Your Brain When You Meditate



When we meditate, our brain and body enters a deeper state of relaxation. Physiologically, this is reflected by a decreased heart rate, blood pressure, skin conduction (a measure of autonomic nervous system reactivity), metabolic activity at the cellular level, and blood levels of lactate, cortisol, and epinephrine. [1] Similarly, our brains become less active as well. Beta waves, which indicate that our brain is processing information, significantly decrease after a single 20-minute meditation session. In the image below, we see a visual representation of this - beta waves, shown on the left, are dramatically reduced during meditation, shown on the right [2].

The following areas of the brain are impacted in different ways:

Frontal Lobe
The most evolved part of the brain, this area is responsible for higher order processing such as reasoning, planning, and self-conscious awareness. Activity in this region is reduced during meditation.

Parietal Lobe
This region of the brain is involved in processing sensory information about your environment, and helps orient you to time and space. In meditation, activity here is reduced.

Thalamus
The brain's computer circuit, this area of your brain focuses your attention by filtering sensory data deeper into the brain. Meditation significantly reduces the flow of sensory input into this area, thus decreasing activity in the thalamus.

Reticular Formation
The reticular formation is the center in your brain that keeps you alert and ready to respond. Meditation turns down the signal here. [3]

Meditation changes the structure of your brain

One of the most cited studies regarding meditation effects on the brain came from Harvard in 2011, when Sara Lazar and her team found that mindfullness meditation actually changes the structure of your brain. Her study participants completed eight weeks of a mindfullness based stress reduction program and were followed with before and after fMRI brain images. Her team found that the study participants who completed the meditation program were found to have an increased gray matter density in the region of their hippocampus - a brain region implicated in learning and memory. Further, they found that these same individuals had a decreased neuronal volume in the amygdala - a brain region that drives fear, anxiety, and stress. These objective changes in brain structure matched the participants' self-reports on stress levels, suggesting that meditation not only physically changes our brains, but also changes our perception and feelings as well. In following up with these participants, Lazar and her team discovered that changes in brain areas linked to mood were also correlated with improvements in participant's rating of their psychological well-being. [4]

Meditation Effects on Anxiety and Depression

Dr.Madhav Goyal and his team at Johns Hopkins University School of Medicine explored the effects of meditation on mental health by conducting a review of 47 clinical trials among over 3,500 participants. The research they analyzed involved meditation and various mental and physical health issues including depression, anxiety, stress, insomnia, substance use, diabetes, heart disease, cancer, and chronic pain. Ultimately, they found that 30 minutes of daily mindfullness meditation for eight weeks provided as much relief from depression symptoms as antidepressants. That is, meditation was able to reduce depression as effectively as some pharmaceutical drugs. [5]

Meditation Effects on the Default Mode Network

A particularly interesting study from Yale University found that mindfullness meditation reduces activity in the Default Mode Network (DMN). The DMN is a neuronal network in the brain that has been shown to be a driver of mind-wandering (aka daydreaming) and self-referencing. Research has suggested the DMN is active when we're not aware of our thoughts - that is, the DMN is "on" when our minds are floating through endless worries and thoughts about the past or future. Studies have shown that mind-wandering, as opposed a state of awareness in the present moment, is associated with being less happy. Because of this, the goal for many people is to dial this sort of daydreaming down. Mindfullness meditation appears to do just that. Not only do meditators have less persistent activity in the DMN, but they also have stronger connectivity between different parts of the DMN that allows them to snap out of mind-wandering states faster than those who don't meditate. [6]

Meditation Improves Concentration and Attention

Michael Mrazek and colleagues completed a study that evaluated the effects of meditation on working memory capacity, mind wandering, and GRE performance. Just 2 weeks of meditation helped participants focus, decreased the intrusion of distracting thoughts, improved memory, and improved verbal reasoning scores on the GRE by 16 percentile points. In their population, those participants who were prone to distraction during pretesting reported reduced mind-wandering during testing. [7]

Meditation certainly is not a panacea, but it undoubtedly has salient benefits. It seems that much of what we are discovering through research in the neurosciences is validating the anecdotes we've come across. In the context of our country's recent trend towards wellness, meditation is proving to be a particularly simple, practical, and effective practice. Now if you're looking to reap the rewards of meditation, I'd be remiss if I didn't preach the importance of habitual practice. Much of the research highlighted above is grounded in the neuroscientific principle of plasticity. That is, our brains are remarkably dynamic, and remain so throughout our adult life. This characteristic is responsible for our ability to learn. Whether it be a playing a new musical instrument or mastering a new language, our brains are continuously rewiring. If we apply this to meditation, it stands to reason that if our brains are structurally changed by meditation (and these changes are reflected by the plentiful benefits we experience), these same changes will be lost if we stop meditating. Now who wants that? Hopefully this sheds a new light on what you already know or don't know about this ancient practice, and encourages you to prioritize your mental wellness through the regular practice of meditation.

REFERENCES:

1. Wallace RK. Physiological Effects of Transcendental Meditation. Science 167:1751-4,1970.
2. The Norwegian University of Science and Technology (NTNU). "Brain waves and meditation." ScienceDaily. ScienceDaily, 31 March 2010. .
3. Jacobs, Gregg D. The Ancestral Mind: Reclaim the Power. New York: Viking Press, 2003
4. Hölzel BK, Carmody J, Vangel M, et al. (2011). Mindfulness practice leads to increases in regional brain gray matter density. Journal of Psychiatry Research. 191(1): 36-43.
5. M. Goyal, S. Singh, E. M. Sibinga, N. F. Gould, A. Rowland-Seymour, R. Sharma, J. A. Haythornthwaite, et al. (2014) Meditation Programs for Psychological Stress and Well-Being: A Systematic Review and Meta-Analysis. JAMA Internal Medicine 174 (3): 357-386.
6. Brewer, J. A., P. D. Worhunsky, J. R. Gray, YY Tang, J. Weber, H. Kober. (2011) "Meditation experience is associated with differences in default mode network activity and connectivity." PNAS 108(50): 20254-9.
7. MD Mrazek, MS Franklin, DT Phillips, B Baird, JW Schooler. (2013) Mindfulness training improves working memory capacity and GRE performance while reducing mind wandering. Psychological science 24 (5), 776-781.




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