In Canada, the annual prevalence of major depressive episodes is 4.7% 1. Depressive disorders are the second leading cause of
disability worldwide 2. Despite recent advances, more than 1 in 5 Canadians with depression have treatment-resistance and fail to remit
with multiple trials of pharmacologic therapies 3. Transcranial direct current stimulation (tDCS), which uses low amplitude electrical
current to modulate synaptic transmission, is safe, can be delivered in an outpatient setting without need of anaesthesia, and is a
promising treatment option for such individuals 4.
Here, we present the initial results of an ongoing randomized trial examining the effectiveness of tDCS and tDCS enhanced by audiovisual
entrainment (etDCS) as compared to treatment-as-usual in the care of patients with ultra treatment-resistant unipolar or bipolar
depression. Individuals are eligible for inclusion if they have a current score >34 on the Montgomery Asberg Depression Rating Scale
(MADRS), and have failed to remit despite receiving electroconvulsive therapy, ketamine, previous trials with at least five
antidepressants, or with the simultaneous use of two mood stabilizers (for bipolar depression). The intervention consists of 2 mA of
current directed over the left dorsolateral prefrontal cortex for 30 minutes a day, for a total of 30 treatment sessions. The primary
outcome is improvement on the MADRS, with secondary outcomes including improvement on the Quick Inventory of Depressive
Symptomatology - Self Report 16 (QIDS-SR16), the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0), and
an exploratory analysis of patient-reported side-effects.