I am doing research for a new post about TM and groups in Latin America and just found this interesting piece of research:
The use of the Transcendental Meditation programme in the prevention of drug abuse and in the treatment of drug-addicted persons
G. CLEMENTS Vice- Chancellor and Professor of Physics, Maharishi University of Natural Law, Buckinghamshire, United Kingdom of Great Britain and Northern Ireland
L. KRENNER Austrian Medical Association-TM, Vienna, Austria
W. MÖLK Austrian Association of Ayurvedic Medicine, Vienna, Austria
ABSTRACT The effectiveness of Transcendental Meditation (TM) in the prevention and reduction of drug abuse has been documented in many studies in the last 18 years. The programme is not a rehabilitation programme per se but is a means for self-development. Thus, the resulting decrease in psychological problems and drug abuse is an automatic or secondary consequence of the practice of the meditation technique. Since TM strengthens the individual and produces an overall and stable state of well-being, it naturally removes the need and craving for drugs.
Read more here.