Evaluation of Temporal Interference in Target Engagement of Subgenual Cingulate Cortex in the Treatment of Major Depressive Disorder

Major Depressive Disorder (MDD) has a high prevalence, is the leading cause of disability, and currently available interventions are associated with side effects and high treatment resistance. There is an urgent need for the development of novel interventions for MDD with alternate mechanisms of action. Temporal Interference (TI) stimulation is a newly emerging form of transcranial alternating current stimulation (tACS) that involves the application of two high-frequency currents at slightly different kHz frequencies. Since neurons, due to their intrinsic low-pass filtering, do not respond to high frequencies (i.e. > 100 Hz), TI relies on the 'beat' interaction leading to neuromodulation at any given location, resulting in a much smaller focus and allowing for better targeting. The subgenual cingulate cortex (SCC) appears to be critical in the pathophysiology of depression and treatment response, especially in treatment-resistant cases. Non-invasive treatments, however, are not able to accurately target SCC due to its deep location within the brain. In this trial, 30 participants meeting the diagnostic criteria for MDD will be randomized to receive 10 sessions of 130 Hz TI delivered daily for 30 minutes, or 10 sessions of sham stimulation. During the stimulation, participants will be watching emotional film clips to enhance target engagement. The investigators will collect metrics of SCC target engagement using the resting-state fMRI and EEG technologies, and determine feasibility, tolerability, safety, and therapeutic efficacy of TI stimulation in MDD. The results of this trial will inform the TI technology as a therapeutic tool for network-based psychiatric disorders, including MDD, and be vital for the design and development of a large-scale randomized-controlled trial.