THE USABILITY OF ADD-ON TRANSCRANIAL DIRECT CURRENT STIMULATION IN MAINTENANCE NEUROMODULATION TREATMENTS – A CASE SERIES

Background: Electroconvulsive therapy (ECT) and repetitive transcranial magnetic stimulation (rTMS) are commonly used to treat treatment-resistant depression (TRD). Due to the large risk for relapses after acute treatment, maintenance ECT and rTMS are often needed. Their numbers are increasing, consuming the resources and possibly leading to increased waiting times for acute treatment. Therefore, it is important to study possible interventions to decrease the need for maintenance ECT and rTMS in depression. Add-on transcranial direct current stimulation (tDCS) is one option for this, but there are no previous studies on combining tDCS to maintenance ECT or rTMS treatment. Objectives: In this clinical case series, we describe a clinical development project aimed to investigate the usability and effects of add-on tDCS for depression patients receiving or fulfilling the indication for maintenance ECT or rTMS. Methods: Patients (n=12) with unipolar depression, without current acute suicidality or psychosis being treated with or fulfilling the indication for maintenance ECT or rTMS, were offered the possibility of tDCS in addition to or instead of the ongoing maintenance treatment. tDCS started with a 6 week (w) acute treatment, with control visits/phone calls at 1w, 3w and 6w from the start. The patients took 5-7 tDCS treatments per week at home. At 6w, tDCS was stopped or continued, with control visits/phone calls every 6w. We collected data from the medical records from baseline, 3w, 6w and 6-month check-ups. We analysed patients’ adherence (whether they used tDCS), subjective view of the treatment, adverse effects, and if adding tDCS improved the clinical status, reduced the severity of symptoms and affected the frequency of rTMS or ECT maintenance treatment sessions. Due to small sample, no tests on statistical significance were done. Results: During the 6w acute tDCS treatment, mean BDI and GAD-7 scores decreased, and the majority of the patients benefitted from the treatment. There were minor side effects. During the 6-month follow-up, the number of both ECT and rTMS maintenance treatments decreased compared to the 6-month period before the intervention (ECT –1.8 sessions and rTMS –8 sessions). Conclusions: tDCS may be a potential treatment for decreasing the need for maintenance ECT or rTMS for TRD patients. More studies of longer duration, larger study population and with placebo control are needed to verify this. Furthermore, the costeffectiveness of add-on tDCS needs to be studied.