International Study to Predict Optimised Treatment - in Depression

This is an open-label, randomised (effectiveness) study (ie. comparison of active treatments) to identify genetic markers, brain function, brain structure, and psychological and cognitive indicators (or a combination of markers) in MDD subjects versus healthy controls. Approximately 2,016 subjects with major depressive disorder (MDD) across multiple international sites (USA, Canada, UK, South Africa, New Zealand, The Netherlands and Australia) will be randomised to one of three approved and effective treatment arms: Treatment A Escitalopram. Treatment B Sertraline. Treatment C Venlafaxine XR. A group of matched healthy controls (n = 672) will also be enrolled. Subjects will be asked to attend the testing facility on two separate occasions; for Pre-treatment (Pre-Tx) and at 8 weeks post initiation of treatment. The assessments/procedures at Pre-Tx and Week 8 include: Baseline a clinical work-up, blood collection for genetic analyses, cognitive testing and electrical brain functioning (EEG/ERP). Structural and functional data MRI data will be collected in ten percent (10%) of participants. On Day 4 and Weeks 2, 4, 6, 12, 16, 24 and 52 Subjects will be contacted by phone and asked to complete 2 questionnaires via the internet.