A Cochrane review included 18 studies with a total of 1215 participants. They examined effects of music therapy over the short (up to 12 weeks, 10 studies), medium (13 to 26 weeks, 7 studies), and long-term (6 months, 1 study), with treatment dosage varying from 7 to 240 sessions. A positive effect on global state was found for music therapy compared to standard care (medium term, RR 0.38 95% CI 0.24 to 0.59; 2 RCTs, n = 133). Medium-term continuous data identified good effects for music therapy on negative symptoms using the Scale for the Assessment of Negative Symptoms (SMD - 0.55 95% CI -0.87 to -0.24; 3 RCTs, n = 177). General mental state endpoint scores on the Positive and Negative Symptoms Scale were better for music therapy (SMD -0.97 95% CI -1.31 to -0.63; 2 RCTs, n = 159), as were average endpoint scores on the Brief Psychiatric Rating Scale (SMD -1.25 95% CI -1.77 to -0.73; 1 RCT, n = 70). Medium-term average endpoint scores using the Global Assessment of Functioning showed no effect for music therapy on general functioning (SMD -0.19 CI -0.56 to 0.18; 2 RCTs, n = 118). However, positive effects for music therapy were found for both social functioning (Social Disability Screening Schedule scores; SMD -0.72 95% CI -1.04 to -0.40; 2 RCTs, n = 160), and quality of life (General Well-Being Schedule scores: SMD 1.82 95% CI 1.27 to 2.38; 1 RCT, n = 72). There were no data available for adverse effects, service use, engagement with services, or cost.
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions) and indirectness (short follow-up time).