Efficacy of Transcranial Direct Current Stimulation (tDCS) for the Treatment of Major Depressive Disorder

Efficacy of Transcranial Direct Current Stimulation (tDCS) of Dorsolateral-prefrontal Cortex as an Add-on Treatment for Drug-naïve Major Depressive Disorder: A Randomized, Double-blind, Sham-controlled Trial

The aim of this study is to assess the efficacy of Transcranial Direct Current Stimulation (tDCS) as an Add-on Treatment for the drug-naïve Major depressive disorder. Meanwhile, evaluate the effect of tDCS on cognitive function of drug-naïve MDD patients. Furthermore, the investigators will examine the changes in cortisol, gut microbiome and some biomarkers. The hypothesis of this study is that tDCS alleviate the depressive symptoms and improve the cognitive function of drug-naïve Major depressive disorder patients with regulating inflammatory response.

This is a randomized, double-blind, sham-controlled study using transcranial Direct Current Stimulation (tDCS) for 4-week treatment. After the intervention of tDCS, there is a follow up visit at week 8 in order to understand the long-term effects of tDCS. Participants were randomly assigned 1:1 to tDCS group or sham-control group. Active tDCS comprised 20 min sessions of 2 mA direct current delivered over the dorsolateral prefrontal cortex, 5 days per week, for 4 weeks. Sham was administered similarly, but with current turned off after 30s. Apart from studying the effects of tDCS on severity of depression and cognitive function, the secondary outcomes are to examine biomarkers related to inflammatory activity. Scale assessments are performed before the initiation of treatment, week 1, week 2, week 3, week 4 and week8. Collection of blood, excrement and saliva takes place at three time points, at the baseline, week 4 and week 8.

Inclusion Criteria:

• a current episode of MDD diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)
• age between 18 and 50 years
• a total score of HAMD-17 ≥ 17
• take antidepressants less than 3 days
• Patients are compliant with treatment according to the judgement of the treating clinician.

Participant or guardian has to sign informed consent. The patients' guardians will sign the informed consent on behalf of the participants when the capacity of participants to consent is compromised.

Exclusion Criteria:

• A history of manic episode
• Use of mood stabilizer
• History of substance abuse or dependence
• Severe somatic diseases that might interfere with regular antidepressant treatment including conditions such as kidney and liver failure, uncontrolled hypertension, cardiovascular, cerebrovascular and pulmonary disease, thyroid disease, diabetes, epilepsy and asthma.
• Use of anti-inflammatory medication for longer than 7 days in the last two months preceding the trial
• Use of immunosuppressive medication such as oral steroid hormones Women in pregnancy or lactation period