The investigators purpose is to follow remitted patients from their previous study using transcranial direct current stimulation (tDCS); as to verify whether this treatment prevents relapse.

Our first ongoing study (Efficacy Study of Transcranial Direct Current Stimulation (tDCS) to Treat Major Depressive Disorder) addresses whether tDCS is an effective treatment for depression treatment. The purpose of the present study is to determine whether tDCS is also an effective strategy for sustaining remission.

We will enroll patients who presented remission using tDCS from our previous study and offer them to tDCS every other week for three months, than once a month for another three months. We will address whether tDCS prevents relapse by assessing depression scores once a month, using a time-to-event analysis.

The importance of the present study is to determine whether tDCS is able to sustain remission during long-term follow-up of depressed patients.

Inclusion criteria:

Patients from previous studies (ID:USP-HU-001 and ID:USP-HU-002) who:

• received tDCS and responded.
• received tDCS + sertraline and responded.
• received sertraline or placebo and did not respond, and thereafter received tDCS during the cross-over phase and responded.

Exclusion criteria:

Patients from previous studies who:

• received tDCS and did not respond.
• received tDCS + sertraline and did not respond.
• received sertraline or placebo and responded.
• did not respond during the crossover phase.
• do not wish to participate in the present study.