Yoga Effects on Brain Health: A Systematic Review of the Current Literature

Abstract

Yoga is the most popular complementary health approach practiced by adults in the United States. It is an ancient mind and body practice with origins in Indian philosophy. Yoga combines physical postures, rhythmic breathing and meditative exercise to offer the practitioners a unique holistic mind-body experience. While the health benefits of physical exercise are well established, in recent years, the active attentional component of breathing and meditation practice has garnered interest among exercise neuroscientists. As the scientific evidence for the physical and mental health benefits of yoga continues to grow, this article aims to summarize the current knowledge of yoga practice and its documented positive effects for brain structure and function, as assessed with MRI, fMRI, and SPECT. We reviewed 11 studies examining the effects of yoga practice on the brain structures, function and cerebral blood flow. Collectively, the studies demonstrate a positive effect of yoga practice on the structure and/or function of the hippocampus, amygdala, prefrontal cortex, cingulate cortex and brain networks including the default mode network (DMN). The studies offer promising early evidence that behavioral interventions like yoga may hold promise to mitigate age-related and neurodegenerative declines as many of the regions identified are known to demonstrate significant age-related atrophy.

Keywords: Cognition; brain; yoga review.

Fig.1

Search results from PubMed featuring the term “yoga” in the title and/or abstract of publications over the years shows an exponential growth in yoga research beginning in the 2000s.

Fig.2

Prisma flowchart.

Fig.3

Brain regions showing A) structural differences in yoga-practitioners compared to non-practitioners or B) a dose-dependent relationship between years of yoga practice and brain structure among practitioners. Yoga practitioners exhibited greater cortical thickness, gray matter (GM) volume, and GM density than non-practitioners in a variety of regions. Among yoga-practitioners, a positive relationship between the years of yoga practice and GM volume was also observed in a number of areas. All but one of the regions shown were created by making a 5 mm sphere around the coordinates provided in the studies reviewed. Since Gothe et al. (2018) did not investigate volume differences on a voxel-wise basis, a mask of the whole structure is shown.

Fig.4

Brain regions showing differential task-related activation in yoga-practitioners. Yoga practitioners showed less activation than non-practitioners in the left dorsolateral prefrontal cortex during the encoding phase of a Sternberg Working Memory task (yellow). Yoga practitioners also showed less activation than non-practitioners in the right dorsolateral prefrontal cortex and right superior frontal gyri, but more activation in the left ventrolateral prefrontal cortex during various aspects of an Affective Stroop task (red). All regions shown were created by making a 5 mm sphere around the coordinates provided in the studies reviewed.