 Over 30-36 months, five Toronto academic sites with a history of successful collaboration will enroll and randomize: 1 125 participants age 60 and older with MCI; and 2 250 participants age 65 and older who have been successfully treated for an episode of MDD defined as a major depressive episode occurring for the first time in late life or that recurs in late life with or without MCI. These 375 participants will be randomized under double-blind conditions to receive either tDCS CR or sham tDCS sham CR and followed for 24-60 months. 