The evolving randomised controlled trial in mental health: studying complexity and treatment process

As a gold-standard methodology for the testing of the effectiveness of health treatments, the randomised controlled trial (RCT) continues to evolve to meet the challenges of new contexts and areas of medicine. This article reviews two particular evolving features of RCTs that make them increasingly well adapted to testing psychological interventions in mental health. The first is a new confidence that RCTs can be successfully adapted to test the more complex (often psychosocial) health interventions and technologies. The second is an increasing emphasis on using the RCT method to explore many facets of the process of treatment as well as its outcome. These two developments should help the RCT method to come of age in mental health, increase the face validity of the RCT method for practitioners and aid the effective translation of research work into improvements in practice.