Please find links here to articles and researches on the benefits of Ashtanga Yoga and Yoga in general:
BBC article on Ashtanga Yoga: http://news.bbc.co.uk/1/hi/health/1620548.stm
http://www.yogaflavoredlife.com/wellness/ashtanga-yoga-for-kids-physical-and-mental-health.html
Same article as above but from different source – Direct Science
http://www.associatedcontent.com/article/2448064/ashtanga_yoga_the_healithiest_way_of.html?cat=50