This study uses a double-blind, placebo-controlled, randomised between-groups design to test if adjunctive administration of a serotonin receptor subtype 4 (5HT4) agonist called PF-04995274 has positive effects on emotional processing and neural activity in medicated treatment-resistant depressed patients. Participants are patients who fulfill criteria for current episode of Major Depressive Disorder (MDD) and have shown lack of response to antidepressant treatment, and they will be randomised to receive 7 days treatment with either PF-04995274 (15 mg daily) or a matched placebo. Participants will come for a Screening Visit, a First Dose Visit, and a Research Visit (including measures of emotional processing and non-emotion cognition).
This study will test whether seven days adjunctive administration of a serotonin receptor subtype 4 (5HT4) agonist called PF-04995274 has positive effects on emotional processing and non-emotional cognition in medicated, treatment-resistant depressed patients compared to placebo.