Transcranial direct current stimulation (tDCS) for depression: analysis of response using a three-factor structure of...

There is growing evidence that transcranial direct current stimulation (tDCS) may be an effective treatment for depression. However, no study to date has profiled the antidepressant effects of tDCS using items or factors on depression symptom severity rating scales. This could potentially provide information about the mechanisms by which tDCS achieves its antidepressant effects and also identify clinical predictors of response.

The present study analysed scores on the Montgomery-Åsberg depression rating scale (MADRS) from a randomised, sham-controlled trial of tDCS (Loo et al., 2012. British Journal of Psychiatry. 200, 52-59) using a three-factor model of MADRS items (Suzuki et al., 2005. Depression and Anxiety. 21, 95-97) encompassing dysphoria, retardation and vegetative symptoms.

Participants in the active tDCS treatment group showed significant improvement in dysphoria while participants in the sham treatment group did not. While both groups showed improvement in retardation symptoms, improvement was significantly greater in the active tDCS group. Both groups also showed improvement in vegetative symptoms but there were no between-group differences.

Further studies with larger sample sizes are warranted to investigate the generalisability of results and whether the MADRS factor structure may change as a result of the specific treatment used.

tDCS appears to be particularly effective in treating dysphoria and retardation, but not vegetative symptoms of depression. This may have implications for selection of types of depression most likely to respond to this treatment.