Transcranial Direct Current Stimulation (tDCS) in Young Individuals with Major Depressive Disorder: a Literature Review and Feasibility Study

Objectives: (1) To assess the therapeutic effects of tDCS on improving depressive symptoms in young individuals with Major Depressive Disorder (MDD), relative to sham stimulation ; and (2) to evaluate the tolerability, and feasibility of tDCS in young individuals with Major Depressive Disorder, to explore the feasibility for a scale-up study.

Hypothesis: 1) we hypothesize the tDCS stimulation of the dorsolateral prefrontal cortex (dLPFC) will reduce symptoms of depression more than sham stimulation, demonstrated by significant difference in change of Hamilton Depression Rating Scale (HDRS) and 2) tDCS active stimulation of the dLPFC will be tolerable and feasible among patients with MDD, as demonstrated by minimal adverse effects measured in the Adverse Events Questionnaire, adherence (with reasons of drop out), their motivation and enjoyment to participate in the study .

The incidence of probable depression during the fifth peak of COVID-19 was 24.6%, within the HK population, with the youths having experienced a disproportionately higher rate. A recent epidemiology survey conducted in HK revealed the 12-month prevalence of suicidal ideation among young individuals above secondary school age to be an alarming 8.4%. While guidelines and RCTs support the use of medication and psychotherapy as a standalone or combination treatments for major depressive disorder (MDD) in youths, a large proportion do not respond to either medication or psychotherapy. There is therefore an unmet need for new, effective treatment options for depression that can be tolerated by young individuals. Transcranial direct current simulation (tDCS) has its acute-effect is physiological change that reduces the threshold of membrane polarisation and increased the synaptic excitability. A handful of studies suggested that anodal stimulation of the dorsal lateral prefrontal cortex (DLPFC) is effective in reducing depressive symptoms in adults, however, whether similar effects applies to youth remains unknown. tDCS is portable, relatively inexpensive, and easy to use, proving to be very safe and tolerable for young individuals with minimal and temporary side effects.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosed with major depressive disorder (MDD) according to the Structured Clinical Interview for DSM-5, Clinical Version (SCID-DSM-5, CV)
* Scored ≥ 14 (i.e., at least mild to moderate depression on the 17-item Hamilton Depression Rating Scale (HDRS) at screening and at baseline;
* Right handedness;
* Stable dosage of antidepressants or other treatments for depression in recent 4 weeks; and
* Can read and write Chinese.

Exclusion Criteria:

* History of significant head trauma, neurological disorders (e.g., epilepsy), seizures;
* First degree relative with epilepsy;
* Concomitant unstable medical conditions; major neurological conditions;
* Comorbid disorders listed in the DSM-V, e.g., schizophrenia, substance use disorder, mental retardation, etc.;
* Pregnancy, lactating women, or women planning pregnancy;
* Device or metal clips on or inside the skull, cardiac pacemaker;
* Inability to provide informed consent.