Evaluating tDCS Brain-stimulation in Depression Using MRI

Patients, physicians, and those who fund depression research are keenly interested in depression treatments that do not involve taking medications. One promising candidate treatment is transcranial direct current stimulation (tDCS), a low-cost technique that involves placing electrodes on specific scalp locations and using a 9-volt battery to cause a small amount of electricity to pass through parts of the brain. Depending on the direction of electrical flow, tDCS can make brain cells (neurons) more likely or less likely to generate their own electrical signals. When evaluated as a treatment, tDCS is typically done in daily sessions over a period of two weeks.

One of the challenges of tDCS is to work out the best possible positioning of electrodes and direction of electricity flow to gradually cause lasting changes in brain activity in ways that might be expected to improve depression. To address this challenge, the investigators are using MRI to take pictures of the brain during tDCS. This data will help us better understand the short-term effects of tDCS in depression and help us learn how to customize future treatments to cause a lasting beneficial response.

Patients with depression between the ages of 20-55 years are eligible to take part in this research. Potential participants will undergo:

1. An assessment to confirm eligibility. This will take place over a secure videoconference call lasting no more than 3 hours. 2. Two in-person study visits lasting 30 min and 2-1/2 hours respectively. In the first visit, the investigators will use the MRI to take a picture of the brain and head structure to determine appropriate locations for placing the tDCS electrodes at the start of the second visit. Following electrode placement, an MRI scan will be performed to take pictures of the brain during tDCS. Depending on the study arm,

1. Participants may receive 'active' or 'sham' tDCS. The 'sham' condition is identical to the 'active' tDCS in every way except that it involves minimal tDCS and is designed to help rule out effects unrelated to the administered tDCS electricity. 2. Participants may also be asked to perform a mental task during MRI.