5. Has a history of failure to respond to 1, 2, or 3 FDA-approved antidepressants at adequate doses during the current episode for at least 8 weeks, as defined by the MGH Antidepressant Treatment Response Questionnaire (MGH-ATRQ), and must be currently on the failed SSRI for at least 8 weeks and on a stable dose for at least 4 weeks.