Yoga may help keep the brain healthy, research suggests.
While the cognitive benefits of rigorous exercise have long been known, the effects of calm stretching were less understood.
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To learn more, scientists from the University of Illinois looked at 11 studies that analysed the link between yoga and brain health.
The ancient Indian practice was found to increase the size of the participants’ hippocampus in several of the studies. This is associated with memory and shrinks in dementia sufferers.
Others areas of the brain responsible for everything from regulating emotions to decision making were also larger in those who practiced yoga.
The gentle work out is thought to reduce stress, which is “known to detrimentally impact both cognitive functioning and brain structure”.
Yoga is the most popular “complementary therapy” in the US, practiced by more than 13 million adults, according to the National Center for Complementary and Integrative Health.
While some poses can be relatively strenuous, it is generally classed as “light intensity” under the American College of Sport Medicine’s criteria, the scientists wrote in the journal Brain Plasticity
The NHS recognises yoga has been linked to a reduction in blood pressure, pain relief and better mood.
It adds, however, there is “scope for more rigorous studies on its health benefits”.
Of the 11 studies analysed, five were made up of yoga novices, who took part in at least one session a week over 10-to-24 weeks. MRI scans were taken before and after.
The other studies compared the brain scans of yoga aficionados and those new to the work out.
“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,” co-lead author Professor Neha Gothe said.
“For example, we see increases in the volume of the hippocampus with yoga practice.”
The hippocampus shrinks with age, and is “the structure first affected in dementia and Alzheimer's disease”.
Past research suggests the prefrontal cortex and brain networks like the default mode tend to be larger in those who practise yoga.
“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,” co-lead author Professor Jessica Damoiseaux said.
“The default mode network is a set of brain regions involved in thinking about the self, planning and memory.”
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Brain changes seen in yoga fans have also been associated with better performance on cognitive and “emotion regulation” tests.
The scientists were surprised to find the ancient practice had similar effects on the brain to more rigorous work outs.
“Yoga is not aerobic in nature, so there must be other mechanisms leading to these brain changes,” Professor Gothe said.
“So far, we don't have the evidence to identify what those mechanisms are.”
The team suspect the calming effects of yoga may help people regulate their emotions, which could have a positive impact on the brain.
“In one of my previous studies, we were looking at how yoga changes the cortisol stress response,” Professor Gothe said.
“We found 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.
“The practice of yoga helps improve emotional regulation to reduce stress, anxiety and depression, and that seems to improve brain functioning.”
The scientists are calling for more research into how yoga affects the brain.
“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,” Professor Damoiseaux said.