Transkranielle Gleichstromstimulation (tDCS) als Zusatzbehandlung bei behandlungsresistenter Depression (TRD)

Participants will receive a 30-minute tDCS treatments at 2 mA twice daily over the course of 5 days.

tDCS is a form of noninvasive transcranial stimulation of the brain by delivering low-intensity electrical current to the scalp through two electrodes. The Soterix Medical 1×1 Low Intensity Transcranial DC Stimulator Model 1300A (Soterix Medical, Inc., New York, NY, USA) device will be used in the study. The tDCS device is comprised of a small battery-operated control box that delivers the current through electrodes placed on the scalp, held in place by elastic bands or head straps and worn over the forehead like a headband.

Defined as 70% of eligible patients choosing to enroll in the study. Other feasibility parameters will include willingness of clinicians to refer and help recruit patients, number of eligible participants, willingness of participants to enroll, retention of patients, and completeness of data collection.

Defined as 80% of study participants completing 80% of the 10-session tDCS treatment protocol. Investigators will also ask participants about their satisfaction, perceptions, and experiences with the tDCS treatments. Other acceptability parameters will include rates of adherence to tDCS protocol, dropout rates and reasons for non-completion.

Defined as an overall tolerability rating of "very tolerable." This will be a self-report based on a global question "Considering all aspects of your experience, how would you rate the overall tolerability of the tDCS intervention?" The response options are: very tolerable, somewhat tolerable, neutral, somewhat intolerable, and very intolerable. Other tolerability parameters will include the tDCS adverse effects questionnaire.

Measure of depressive symptoms. Response is defined by a 50% or more reduction in MADRS score. The MADRS has 10-items which are based on mood symptoms. Each items is scored 0 (normal) to 6 (severe depression) with overall score ranges from 0 (normal) to 60 (severe depression).

Measure of anhedonia. The SHAPS has 14-items which are based on pleasure symptoms. Each item is scored 1 (definitely agree) to 4 (definitely disagree) with overall score ranges from 14 (experience high pleasure) to 56 (experience low pleasure)

Measure of measure memory and executive function. Reaction time (in seconds) in the different conditions of the task (reading the non-conflicting condition, reading the conflicting condition)

Measure of verbal learning and memory. The HVLT-R has 12-items which are based on memory score. Total recall score (range from 0 to 36). The higher the score indicates better short-term memory, lowers scores indicates worse short-term memory.

Measure of working memory. The DSST involves a key consisting of the numbers 1-9, each paired with a unique, easy to draw symbol. Below the key are a series of numbers that 1-9 in random order and repeated several times, that are to be filled in the corresponding symbol for each number. One point is given for each correct response. Total scores range from 0-9, lower scores indicate worse memory; higher scores indicate better memory.

EEG measure of the highest magnitude within the alpha range of brain oscillations, thought to reflect cognitive performance.