CHICAGO, Dec. 12 (Xinhua) -- A science review posted on the website of the University of Illinois (UI) on Thursday finds evidence that yoga enhances many of the same brain structures and functions that benefit from aerobic exercise.
The review 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 to 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.
Each of the studies used brain-imaging techniques such as MRI, functional MRI or single-photon emission computerized tomography. All involved Hatha yoga, which includes body movements, meditation and breathing exercises.
"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," said UI kinesiology and community health professor Neha Gothe, who led the research with Wayne State University psychology professor Jessica Damoiseaux.
"We see increases in the volume of the hippocampus with yoga practice," Gothe said. 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, Gothe said. "It is also the structure that is first affected in dementia and Alzheimer's disease."
Meanwhile, 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.
Like 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.
The studies also found that the brain changes seen in individuals practicing yoga are associated with better performance on cognitive tests or measures of emotional regulation.
"Yoga is not aerobic in nature, so there must be other mechanisms leading to these brain changes," said Gothe.
Gothe suspected that enhancing emotional regulation is a key to yoga's positive effects on the brain. Studies linked stress in humans and animals to shrinkage of the hippocampus and poorer performance on tests of memory.
"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," she said. "The practice of yoga helps improve emotional regulation to reduce stress, anxiety and depression, and that seems to improve brain functioning."
The researchers said there is a need for more and more rigorous research into yoga's effects on the brain.
The review has been published in the journal Brain Plasticity.
