How Does Ashtanga Yoga Affect Our Brain?

Yoga changes activity in some areas of the brain

Background

Researchers and practitioners have all reported that yoga has a wide variety of benefits. Benefits include physical health and wellness changes. Additionally, yoga has mental health benefits such as positive effects on anxiety and depression. But the mechanisms of how yoga creates those positive health benefits are not well understood.

For that reason, this group chose to look at how yoga may affect our brain. Some previous studies have suggested yoga may contribute to an increase in gray matter in the hippocampus and insular cortex. Additionally, yoga seems to increase functional connectivity. Finally, yoga examined in previous studies seemed to increase molecular compounds associated with positive shifts in the parasympathetic nervous system. All of these activities in the brain have a relationship to positive shifts in the parasympathetic nervous system as mediated by the vagal nerve. This is a primary hypothesis for how yoga works. So, this research group was interested in testing a part of that hypothesis by looking at how yoga may affect our brain.

Research question

How does yoga affect our brain?

Research methods

Study participants (sample): 25 total participants

• 84% of sample was female
• Participants were between 24 and 52 years old

All study participants were healthy adults. Study participants in the treatment group were experienced Ashtanga yoga practitioners. The researchers considered participants to be experienced for the purposes of the study if they had done an Ashtanga yoga practice at least three times per week for at least two years. Researchers matched the active control group to people in the yoga treatment group so that the groups were similar in age range, gender, education, and physical activity level.

Those study participants who were in the yoga treatment group completed the Ashtanga yoga primary series as the yoga treatment. The participants in the active control group did an assigned series of physical exercises. Researchers randomly assigned participants to receive a PET/MR scan (positron emission tomography/magnetic resonance) on one of two consecutive days. A PET/MR scan uses a radioactive tracer to create detailed images of metabolic activity in the body. All participants completed a scan before their activity (either yoga or exercise) and again immediately after their activity.

Results

The research team found that glucose metabolism in some areas of the brain was lower at rest (before yoga) for Ashtanga yoga practitioners compared to those participants in the control group. Specifically, there was lower glucose metabolism in the hippocampus, parahippocampus, striatum, amygdala, insula, anterior midbrain, and cerebellum. Researchers reported that the decrease in glucose metabolism in the parahippocampus and full brainstem before yoga (at rest) was inversely related to the number of years someone had practiced Ashtanga yoga.

Interestingly, glucose metabolism for the yoga group increased after a yoga session compared to levels at rest in the cerebellum. The control group did not experience a similar change after completing their assigned exercise routine. The research team did not find any differences in gray matter volume or GABA levels during the experiment. Those parameters weren’t significantly different between groups. They also weren’t significantly different for either group after yoga or exercise when compared with the baseline levels of the same group at rest.

Why is this relevant to yoga practitioners?

As practitioners, we know that yoga affects us because we directly experience its effects. But how it creates those effects is largely unknown. One of the main theories right now, for how yoga works, involves its effects on the parasympathetic nervous system. Specifically, the movements, breath control, and meditative focus that happen in yoga seem to positively affect our nervous system. While it may not change how we do our yoga practice, researchers want to know more about how that happens.

So, in this study researchers looked at some aspects of how yoga may affect our brain. Interestingly, some areas of our brain that yoga impacted were associated with things like mood regulation, affect regulation, and emotional processing. This suggests that yoga may affect our brain which in turn may have positive impacts on our overall ability to respond to stimuli in our life. Unsurprisingly, yoga also affected areas of our brain associated with movement control, balance, body awareness, and proprioception. So, yoga is also likely to positively affect our functional movement in daily life.

Reference citation

Van Aalst, J., J. Ceccarini, G. Schramm, D. van Weehaeghe, A. Rezaei, K. Demyttenaere, S. Sunaert, and K. van Laere. 2020. Long-term Ashtanga yoga practice decreases medial temporal and brainstem glucose metabolism in relation to years of experience. EJNMMI Research. 10:50.