David A. Richards
David A. Richards is a health services researcher at the University of Exeter Medical School and the chief investigator of the COBRA trial, which assigned 440 adults with depression at random to behavioural activation or to cognitive behavioural therapy, and followed them for a year. The two treatments came out level, and behavioural activation cost less, because staff without specialist therapy training could deliver it.
Who they are
Two terms. Behavioural activation is a treatment that works by re-establishing activity and contact with things a person finds rewarding, rather than by working on thoughts directly. A non-inferiority trial, which is what COBRA was, is designed to test whether a cheaper or simpler treatment is no worse than the established one, rather than whether it is better.
This is the kind of trial this site grades highest: large, planned in advance, clearly reported, and answering a question that changes what gets offered to people.
His affiliation was confirmed in the vault on 11 September 2026. He is not the same person as Becky Richards, who also appears in this vault.
Key papers
Richards, D. A., and colleagues (2016). "Cost and outcome of behavioural activation versus cognitive behavioural therapy for depression (COBRA): a randomised, controlled, non-inferiority trial", The Lancet. Chief investigator and first author. Four hundred and forty adults, twelve months of follow-up.
Key ideas
Level, and cheaper, is a result with consequences. If a treatment that does not require a specialist therapist performs as well as one that does, more people can be treated with the same money. That is the finding, and it is about services rather than about mechanisms.
Why this trial is cited here as a standard. It was large enough to detect what it was looking for, its analysis was specified before the data came in, and it reported costs alongside outcomes. Those are the qualities carried at Statistical Power and Preregistration, and most of the psychology literature on this site does not meet them.
It does not settle which approach suits which person. A trial showing two treatments are level on average says nothing about who does better on which, and this site does not extend it that way.
Concepts on this site
Behavioural Activation, the treatment his trial tested
Rumination-Focused CBT, the rival approach
Statistical Power and Preregistration, the standards this trial meets
Sources
- Richards, D. A., and colleagues (2016). The Lancet. COBRA, 440 adults randomised, twelve-month follow-up, non-inferiority design with a cost analysis.
- Vault record, 2026-09-11. Affiliation confirmed: University of Exeter Medical School, chief investigator on COBRA.