Increasingly, yoga practice and meditation have been the focus of research aiming to test their benefits. Recently, Medical News Today have reported on a wealth of studies pointing to many different advantages of yoga and meditation, including countering cognitive decline, acting on genetic factors that predispose individuals to stress, improving lower back pain, and easing depression.
A new paper published in the journal Frontiers in Human Neuroscience now shows that yoga and meditation appear to have a positive effect on the central nervous system as well as the immune system, and that it may improve the individuals' overall sense of well-being.
The study - led by Dr. B Rael Cahn, from the Department of Psychiatry and Behavioral Sciences at the University of Southern California in Los Angeles - was part of a larger body of research addressing different approaches to promoting resilience.
Yoga and meditation may improve resilience
Dr. Cahn and team worked with some of the participants at a 3-month yoga and meditation retreat. At this retreat, the participants engaged in daily meditation and yoga practice, and they followed a vegetarian diet.
Of the 200 participants (both male and female), 98 volunteered to participate in tests measuring particular biomarkers. However, due to a lack of funding, only 38 volunteers (19 male and 19 female) underwent these assessments.
Additionally, due to circumstances that rendered some of the data unusable, biological samples collected from 26 of these volunteers were analyzed.
Many participants had previous experience of practicing yoga and meditation on a frequent basis, including Shoonya and Samyama meditation, Hatha yoga, and pranayama.
The participants were assessed both before and after participating in the yoga retreat. They had to undergo:
- psychometric tests that collected data about their psychological well-being, mindfulness, and psychological involvement
- measurements of the brain derived neurotrophic factor (BDNF), which is a protein that promotes the survival and growth of various nerve cells and is involved in immune response, metabolic regulation, and resilience to stress
- assessment of the "cortisol awakening response" (CAR), which measured the secretion of cortisol, a hormone involved in the interaction between the hypothalamus, pituitary gland, and adrenal gland (also known as the "HPA axis")
- measurements of pro- and anti-inflammatory cytokine levels, which are involved in the functioning of the immune system
After analyzing the data, the team found that engagement in the yoga and meditation practices at the retreat was associated with decreased anxiety and depression levels - as reported by the participants - as well as with an increase in their level of mindfulness.
From a biological point of view, the scientists noted an increase in BDNF plasma levels, as well as a strengthened CAR, suggesting improved resilience to stress factors.
The data also showed an increase of an anti-inflammatory cytokine (interleukin-10) and a corresponding decrease in a pro-inflammatory cytokine (interleukin-12), which led to a reduction of inflammatory processes.
"It is likely that at least some of the significant improvements in both HPA axis functioning as exemplified by the CAR as well as neuroimmunologic functioning as exemplified by increases in BDNF levels and alterations in cytokines were due to the intensive meditation practice involved in this retreat," suggests Dr. Cahn.
Potential benefits to the nervous system
The researchers believe that the various biological improvements gathered from the collected data indicate an enhanced overall sense of physical and psychological well-being.
They highlight that their results may point to an enhanced functioning of certain elements of the central nervous system, a healthier immune system, and a strengthened sense of focus and awareness.
"The observed increased BDNF signaling [is] possibly related to enhanced neurogenesis and/or neuroplasticity, increased CAR likely related to enhanced alertness and readiness for mind-body engagement, and increased anti- and pro-inflammatory cytokines possibly indicating enhanced immunological readiness."
Dr. B. Rael Cahn
Moreover, the researchers suggest that there is a thrilling possibility that some of the effects observed in the aftermath of the retreat suggest that meditation and yoga could stimulate the hippocampus to function better.
"An intriguing possible link between the effects on BDNF and the CAR is hippocampal functional integrity, since increased BDNF levels due to physical exercise has previously been shown to relate with hippocampal neurogenesis and likely relate to its positive effects on well-being and depression," says Dr. Cahn.
Nevertheless, the scientists caution that not all of these positive effects may be due to yoga and meditation. Some, they suggest, may be owed to the individuals' dietary practices, social interaction, or the impact of the yoga and meditation teachers.
Still, Dr. Cahn and his team are excited by the results of their research and believe that they are grounds for further studies on the potential physical and psychological benefits of yoga and meditation.
"To our knowledge, our study is the first to examine a broad range of pro- and anti-inflammatory markers in a healthy population before and after a yoga-meditation intervention. Our findings justify further studies of yoga and meditation retreats assessing for the replicability, specificity, and long-term implications of these findings," Dr. Cahn concludes.