Cytokines plasma levels during antidepressant treatment with sertraline and transcranial direct current stimulation (tDCS): results from a factorial,randomized, controlled trial

Rationale

The inflammatory hypothesis of depression states that increased levels of pro-inflammatory cytokines triggered by external and internal stressors are correlated to the acute depressive state. This hypothesis also suggests that pharmacotherapy partly acts in depression through anti-inflammatory effects. Transcranial direct current stimulation (tDCS) is a novel, promising, non-invasive somatic treatment for depression, although its antidepressant mechanisms are only partly understood.

Objectives

We explored the effects of tDCS and sertraline over the immune system during an antidepressant treatment trial.

Methods

In a 6-week, double-blind, placebo-controlled trial, 73 antidepressant-free patients with unipolar depression were randomized to active/sham tDCS and sertraline/placebo (2?×?2 design). Plasma levels of several cytokines (IL-2, IL-4, IL-6, IL-10, IL-17a, IFN-γ, and TNF-α) were determined to investigate the effects of the interventions and of clinical response on them.

Results

All cytokines, except TNF-α, decreased over time, these effects being similar across the different intervention-groups and in responders vs. non-responders.

Conclusions

tDCS and sertraline (separately and combined) acute antidepressant effects might not specifically involve normalization of the immune system. In addition, being one of the first placebo-controlled trials measuring cytokines over an antidepressant treatment course, our study showed that the decrease in cytokine levels during the acute depressive episode could involve a placebo effect, highlighting the need of further placebo-controlled trials and observational studies examining cytokine changes during depression treatment and also after remission of the acute depressive episode.