The article offers some insight into how:
Yoga increases our capacity for neuroplasticity required for intentional change, and thickens the layers of the cerebral cortex associated with higher learning. Basically, we become more able to learn and adapt by developing our capacity for intentional and sustained concentration.
Yoga reduces stress and creates more balance between the stress and relaxation responses within the body by effectively engaging both the sympathetic nervous system and parasympathetic nervous system through simultaneous concentration and relaxation. In a simplistic sense, we yogis are training ourselves to initiate the relaxation response when we experience stress instead of spinning in fight or flight.
Yoga boosts brain chemicals that promote a sense of wellbeing, reducing anxiety and depression by increasing levels of "happy brain chemicals" like GABA, serotonin, and dopamine, responsible for feelings of relaxation and contentment. It seems that we are self-medicating in the best possible way when we do yoga.
For more information, read the entire article and watch the film: