A statistical meta-analysis of 198 independent treatment outcomes found that Transcendental Meditation produced a significantly larger reduction in tobacco, alcohol, and illicit drug use than either standard substance abuse treatments (including counseling, pharmacological treatments, relaxation training, and Twelve-step programs) or prevention programs (such as programs to counteract peer-pressure and promote personal development). This meta-analysis controlled for strength of study design and included both heavy and casual users. Whereas the effects of conventional programs typically decrease sharply by 3 months, effects of Transcendental Meditation on total abstinence from tobacco, alcohol, and illicit drug ranged from 51%-89% over an 18-22 month period.

Reference I: Treating and preventing alcohol, nicotine, and drug abuse through Transcendental Meditation: A review and statistical meta-analysis, Alcoholism Treatment Quarterly 11: 13-87, 1994.
Reference II: Effectiveness of the Transcendental Meditation program in preventing and treating substance misuse: A review, International Journal of the Addictions 26: 293-325, 1991.