The long-term effects of ABM on symptom severity in patients with recurrent depression: A randomized sham-controlled trial.

Background: The present study reports on long-term outcomes of ABM over one year in self-reported and clinician-rated depression symptoms, anxiety symptoms, and relapse rates.

Methods: We conducted a double-blind randomized sham-controlled trial in 301 participants with recurrent major depression disorder between January 2015 and October 2016 (#NCT02658682). Participants were allocated to ABM or sham condition twice daily for 14 consecutive days. Long-term effects of ABM were assessed by BDI-II, HDRS and BAI at one-, six-, and 12-months follow-up. Relapse rates at 12-months follow-up were also assessed.

Results: There was no long-term effect of ABM (as compared to sham) on clinician-rated depression symptoms, on anxiety symptoms, nor in relapse rates. By 12 months follow-up, there was a small effect on self-reported depression favoring ABM over sham.

Limitations: The lack of an assessment-only condition hinders comparison to natural trajectories of depression symptoms.

Conclusions: The overall long-term effect of ABM was limited, and currently there is no convincing evidence for implementing this as a viable treatment option in clinical populations. We speculate if the sham condition should be replaced by another control condition when investigating the clinical utility of ABM.