We wish to examine this in an investigation of 20 subjects, and hypothesise that tDCS will have an antidepressant effect and produce no neuropsychological impairment. Subjects will receive anodal DC stimulation or sham stimulation over the left prefrontal cortex in a double-blind, placebo-controlled design over 5 days, and then have daily stimulation up to a maximum of 10 active sessions in total. Outcomes will be formally evaluated by depression rating scales and neuropsychological tests.