August/September 2015 (vol. 12/2)

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Research Plus

Decline in CBT efficacy

The effectiveness of cognitive behavioural therapy (CBT) for treating major depressive disorder appears to have diminished since the therapy was first used widely, according to this meta-analysis of 70 research studies published between 1977 and 2014 (17 randomised controlled trials, and 53 within-group studies). CBT effect sizes, measured both by the Beck Depression Inventory (BDI) and the Hamilton Rating Scale for Depression (HRSD) have fallen linearly and steadily with time (p < 0.001 and 0.01 respectively). While remaining significant, effect sizes have dropped by roughly half on average over 35 years. Rates of remission have also declined with time (p < 0.01). One possible explanation is therapists deviating from the evidence-based protocol under the misconception that CBT is easy to learn – proper training, considerable practice and competent supervision remain vital. The review also revealed that women benefit more than men (p < 0.05) and that experienced practitioners achieve better results than student therapists (p< 0.01). Trial methodology has improved over the years.


Occupational Health at Work August/September 2015 (vol. 12/2) pp39