Heart Rate Variability (HRV)-Guided Transcranial Direct Current Stimulation (tDCS)

This technology development project will be informed and guided by initial data collection of human subject data. For this purpose, the investigators will recruit n=100 people with mild to moderate depression in a double-blinded, parallel-arm, sham-controlled data collection period administered at home and using the investigator's remotely supervised (RS) tDCS protocol. Enrolled participants will complete 10 days of 30-minute tDCS (2.0, DLPFC left anodal) using the RS-tDCS protocol. During each daily session, standard HR and impedance-based HR (i-HR), obtained from the tDCS headset, will be collected to identify a possible marker of response to tDCS in depression. Participants will be randomized 2:1 to active vs. sham tDCS.