It is hypothesized that stress causes an imbalance in the autonomic nervous system (parasympathetic under-activity and sympathetic over-activity) as well as under-activity of the inhibitory neurotransmitter, gamma amino-butyric acid (GABA). Low GABA activity occurs in anxiety disorders, post-traumatic stress disorder, depression, epilepsy, and chronic pain. According to the researchers, the hypothesis advanced in this paper could explain why vagal verve stimulation (VNS) works to decrease both seizure frequency and the symptoms of depression.
"Western and Eastern medicine complement one another. Yoga is known to improve stress-related nervous system imbalances," said Chris Streeter, MD, associate professor of psychiatry at BUSM and Boston Medical Center, who is the study's lead author. Streeter believes that "This paper provides a theory, based on neurophysiology and neuroanatomy, to understand how yoga helps patients feel better by relieving symptoms in many common disorders."
An earlier study by BUSM researchers comparing a walking group and a yoga group over a 12-week period found no increase in GABA levels in the walking group, whereas the yoga group showed increased GABA levels and decreased anxiety. In another BUSM 12-week study, patients with chronic low back pain responded to a yoga intervention with increased GABA levels and significant reduction in pain compared to a group receiving standard care alone.
Source : Boston University Medical Center