Investigators from the Department of Music at the University of Jyväskylä, in Jyväskylä, Finland conducted a two-armed, randomized, controlled trial (RCT) with 79 depressed clients who were also experiencing anxiety, in order to compare the impact of standard care versus Music Therapy (MT) in addition to Standard Care (SC), on symptoms.
The purpose of the study was to examine the mechanisms involved in any improvements that might result from Music Therapy, with particular focus on anterior frontotemporal resting state alpha and theta brain waves*.
Measures were taken at intake and after 3 months, using the Montgomery-Asberg Depression Rating Scale and the Hospital Anxiety and Depression Scale, along with EEG results.
The research team found that music therapy significantly reduced both depression and anxiety symptoms.

They explored correlations between anterior EEG, Montgomery-Åsberg Depression Rating Scale (MADRS) and the Hospital Anxiety and Depression Scale-Anxiety Subscale (HADS-A), power spectral analysis (topography, means, asymmetry) and normative EEG database comparisons.
After 3 months of Music Therapy, lasting changes in resting EEG were observed (isignificant absolute power increases at left fronto-temporal alpha, but most distinct for theta (also at left fronto-central and right temporo-parietal leads).
Music Therapy differed from Standard Care, pointing towards decreased relative left-sided brain activity after Music Therapy, as well as reduced anxiety.
Verbal reflection and improvising on emotions in MT may induce neural reorganization in fronto-temporal areas. Alpha and theta changes in frontotemporal and temporoparietal areas indicate MT action and treatment effects on cortical activity in depression, suggesting an impact of MT on anxiety reduction.

Citation:  Fachner J, Gold C, Erkkilä J. Music therapy modulates frontotemporal activity in rest-EEG in depressed clients. Brain Topography. 2013 Apr;26 (2): pages 338-54. j[email protected]