Transcranial direct current stimulation (tDCS) also called microcurrent electrical stimulation or cranioelectrotherapy stimulation (CES), is a technique that applies extremely weak electrical current to the head and neck to treat mental health problems. In a recent blog post I briefly reviewed the evidence for tDCS as a treatment of anxiety, substance abuse and insomnia. This entry is offered as a concise review of the evidence for tDCS for treating depressed mood
How (we think…) it works
Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that applies weak direct current (typically 1 to 2 milli-Amps) to the brain via electrodes placed on the scalp resulting in hyperpolarization or depolarization of underlying neural tissue causing beneficial changes in neurotransmitter receptor function or stimulating synaptic plasticity and neuronal remodeling. TDCS is being investigated as a treatment of depressed mood based on the theory that the application of very weak electrical currents to certain brain regions may have beneficial effects on brain circuits involved in attention, perception, learning and memory that affect mood. This hypothesis is consistent with findings of abnormal cognitive processing in major depressive disorder, bipolar disorder and other psychiatric disorders. Research findings suggest that problems in affective and cognitive processing are related to functional abnormalities in networks linking specific brain regions including the hippocampus, amygdala and prefrontal cortex. It has been suggested that changes in cortical excitability caused by tDCS may last longer than changes induced by transcranial magnetic stimulation, while offering the advantages of portability and fewer adverse effects.
Studies on tDCS in depressed mood
Findings of small sham-controlled studies suggest that antidepressant effects of tDCS are related to changes in affective processing. Limited research findings support that tDCS may have beneficial synergistic effects when combined with antidepressants and that combined treatment might be more effective than medications or tDCS alone. TDCS should be viewed as a promising emerging treatment of depressed mood pending confirmation by large sham-controlled studies. It is important to comment that findings of studies on tDCS for depressed mood are limited by small study size, heterogeneity in outcomes measures and reporting bias resulting in underreporting of non-significant findings.
Few safety problems
Few mild transient adverse effects of tDCS have been reported including burning, itching and tingling sensations at the site of electrode placement.