Search methods for identification of studies
We searched 13 electronic databases and trial registers: 1. Cochrane Central Register of Controlled Trials (CENTRAL); 2. MEDLINE (Ovid) (1950 to present); 3. EMBASE (1980 to present); 4. CINAHL (1982 to present); 5. PsycINFO (1967 to present); 6. AMED (1985 to present); 7. Web of Science (1945 to present) 8.Scopus (1995 to present) 9. The specialist music therapy research database at www.musictherapyworld.net; 10. CAIRSS for Music; 11. ClinicalTrials.gov(http://www.clinicaltrials.gov/); 12. Current Controlled Trials (http://www. controlledtrials.com/); 13. National Research Register (http://www.updatesoftware.com/ National/) Furthermore we hand-searched 12 journals from their first available date until October 2014: 1. Australian Journal of Music Therapy; 2. Canadian Journal of Music Therapy; 3. The International Journal of the Arts in Medicine; 4. Journal of Music Therapy; 5. Journal for Art Therapies in Education, Welfare and Health Care; 6. Music Therapy; 7. Music Therapy Perspectives; 8. Nordic Journal of Music Therapy; 9. Music Therapy Today (online journal of music therapy); 10. Voices (online international journal of music therapy) 11. New Zealand Journal of Music Therapy; 12. British Journal of Music Therapy. We checked the reference lists of the most relevant articles (see S2 File for the full list of search terms and databases).