Contextual Engagement to Enhance Effective Transcranial Direct Current Stimulation: A Theoretical and Mechanistic Perspective.

Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation that delivers a low amount of electrical energy to targeted brain regions. Recently, a tDCS device was approved by the U.S. Food and Drug Administration for treatment of major depressive disorder. Although this is an important step forward, the observed effect size was modest, and finding ways to improve tDCS efficacy is important. One way to do so is to leverage contextual dependence of tDCS effects. tDCS modulates neuronal excitability in a state-dependent manner, and concurrent cognitive, emotional, or behavioral engagement are important contextual factors that might further improve acute and longer-lasting outcomes. The authors outline the theoretical rationale for integrating therapeutic engagement with tDCS and the need for longer follow-up to assess efficacy, drawing on mechanistic insights, and describe a prior use case of tDCS concurrent with a virtual reality context to underscore this use.