Introduction:
Music therapy is an expression promoting, scientific-artistic-creative and independent form of treatment and aims at maintaining, restoring, and furthering physical, emotional, and mental health. This systematic review aims at assessing the effectiveness of music therapy for the treatment of autism spectrum disorder, dementia, depression, insomnia, and schizophrenia. In addition, music therapeutic methods used for these indications are analysed.

Methods:
In an iterative process, first, systematic reviews and HTAs were searched in six databases and yielded 139 hits for 15 psychiatric and further 23 non-psychiatric indications. Second, the Austrian Health Insurance Company (ÖGK, Österreichische Gesundheitskasse) decided to focus on five frequent indications with available Cochrane reviews. For the update of Cochrane Reviews, a second systematic literature search in four databases (Medline via Ovid, Embase, The Cochrane Library, and PsycINFO) was conducted, limited to publications from 2013 to 2020. Two review authors independently performed the study selection and data extraction. For assessing the methodological quality of the included trials, both the Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) and The Cochrane Collaboration's tools were used. For the update, only trials with moderate and low risk of bias were selected.

Results:
Ten randomised controlled trials, involving 1.248 patients, met the inclusion criteria. For the indication schizophrenia, one study with a high risk of bias was found and could not be included. Therefore, an update was not possible. The Cochrane authors stated that quality of life, social functioning and the global and mental state improved in patients with schizophrenia due to MT interventions, while global functioning did not ameliorate. In children with an autism spectrum disorder, music therapy improved behaviour, social communication skills and the parent-child relationship. Patients with depression experienced enhanced moods, and sleep quality improved in patients diagnosed with insomnia due to music therapy. Music therapy positively affects the mood in patients with dementia. Behavioural symptoms enhanced only at the severe Alzheimer's stage. No long-term effects on mood and behavioural symptoms could be found. Cognition increased due to music therapy in only one study out of four studies. Short and long-term memory improved at the mild Alzheimer's disease stage, but not at the moderate or severe stage. Mixed forms of music therapeutic methods were used in patients with dementia, while the authors of the studies on autism spectrum disorder and depression applied active methods. In patients diagnosed with insomnia, only receptive methods were used.

Conclusion:
The findings of this update of reviews provide evidence that music therapy may help patients diagnosed with an autism spectrum disorder, dementia, depression, and insomnia. Music therapy improves physical and psychosocial aspects.