Source: Thailand Medical News Dec 14, 2019 4 years, 11 months, 3 hours, 20 minutes ago
Medical scientists have known for decades that aerobic exercise strengthens the
brain and contributes to the growth of new neurons, but few studies have examined how
yoga affects the brain. A recent review of the science finds evidence that
yoga enhances many of the same
brain structures and functions that benefit from aerobic exercise.
The detailed review, published in the journal
Brain Plasticity, focused on 11 studies of the relationship between
yoga practice and
brain health. Five of the studies engaged individuals with no background in
yoga practice in one or more
yoga sessions per week over a period of 10-24 weeks, comparing
brain health at the beginning and end of the intervention. The other studies measured
brain differences between individuals who regularly practice
yoga and those who don't.
For each of the studies, brain-imaging techniques such as MRI, functional MRI or single-photon emission computerized tomography were utilized. All involved Hatha
yoga, which includes body movements, meditation and breathing exercises.
Dr Neha Gothe, a University of Illinois kinesiology and community health professor who led the research along with Wayne State University psychology professor, Dr Jessica Damoiseaux told
Thailand Medical News, "From these 11 studies, we identified some brain regions that consistently come up, and they are surprisingly not very different from what we see with exercise research. For example, we see increases in the volume of the hippocampus with
yoga practice. Many studies looking at the
brain effects of aerobic exercise have shown a similar increase in hippocampus size over time.
The hippocampus is involved in memory processing and is known to shrink with age, Dr Gothe said. "It is also the structure that is first affected in dementia and Alzheimer's disease."
Although many of the studies are exploratory and not conclusive, the research points to other important
brain changes associated with regular
yoga practice, Dr Damoiseaux said. The amygdala, a
brain structure that contributes to emotional regulation, tends to be larger in
yoga practitioners than in their peers who do not practice
yoga. The prefrontal cortex, cingulate cortex and
brain networks such as the default mode network also tend to be larger or more efficient in those who regularly practice
yoga.
Dr Damoiseaux added, "The prefrontal cortex, a brain region just behind the forehead, is essential to planning, decision-making, multitasking, thinking about your options and picking the right option. The default mode network is a set of
brain regions involved in thinking about the self, planning and memory."
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Similar to the amygdala, the cingulate cortex is part of the limbic system, a circuit of structures that plays a key role in emotional regulation, learning and memory, she said.
The new studies also find that the brain changes seen in individuals practicing
yoga are associated with better performance on cognitive tests or measures of emotional regulation.
The new discovery that
yoga may have similar effects on the brain to aerobic exercise is intriguing and warrants more study, Dr Gothe said.
Dr Gothe added, "Yoga is not aerobic in nature, so there must be other mechanisms leading to these
brain changes. So far, we don't have the evidence to identify what those mechanisms are."
Dr Gothe suspects that enhancing emotional regulation is a key to
yoga's positive effects on the
brain. Studies link stress in humans and animals to shrinkage of the hippocampus and poorer performance on tests of memory, for example, she said.
She added, "In one of my previous studies, we were looking at how
yoga changes the cortisol stress response. We found that those who had done
yoga for eight weeks had an attenuated cortisol response to stress that was associated with better performance on tests of decision-making, task-switching and attention."
Dr Gothe said that
Yoga helps people with or without anxiety disorders manage their stress. "The practice of
yoga helps improve emotional regulation to reduce stress, anxiety and depression," she said. "And that seems to improve
brain functioning."
The medical researchers say there is a need for more rigorous -research into
yoga's effects on the
brain. They recommend large intervention studies that engage participants in
yoga for months, match
yoga groups with active control groups, and measure changes in the brain and performance on cognitive tests using standard approaches that allow for easy comparisons with other types of exercise.
Dr Damoiseaux concluded, "The science is pointing to
yoga being beneficial for healthy brain function, but we need more rigorous and well-controlled intervention studies to confirm these initial findings."
Reference: Gothe, N. P., Khan, I., Hayes, J., Erlenbach, E., & Damoiseaux, J. S. (2019). Yoga Effects on Brain Health: A Systematic Review of the Current Literature. Brain Plasticity, Preprint(Preprint), 1–17. https://doi.org/10.3233/BPL-190084 
