Journal of Psychiatry published this month concluded that the effects had been exaggerated. Two-thirds of people (67 per cent) improved with therapy, which sounds impressive. However, 40 per cent improved without therapy. So the treatment delivered an extra 27 percentage-point "effect".
How has this been exaggerated?
By "publication bias". Publication bias occurs when publishers of medical journals choose to accept trials that show positive results and reject those that show zero or negative results. This skews the published literature to show a larger effect of the treatment than is true in reality. Pim Cuijpers from Vrije University, Amsterdam, who led the review, said that when publication bias is taken into account, it reduces the effect of CBT by "about one-third, to 18 per cent".
So is cognitive therapy worth having?
Probably, given the limited alternatives. Research on antidepressant drugs yields similar results to that for therapy – about two-thirds of patients feel better. But a controversial paper published in 2008 claimed publication bias was also responsible for exaggerating the effects of drugs. The review of 47 trials of six of the best-known antidepressant drugs, including trials that were unpublished, concluded the drugs were no better than placebos in most patients. Only in a very small group of the most extremely depressed were they more effective. The findings, by Professor Irving Kirsch of the University of Hull, published in the online journal Public Library of Science Medicine, have been challenged by a number of researchers.
Is cognitive therapy good for anything else?
Yes. Remarkably, it has been shown to be effective as a treatment for back pain. This is not because back pain is all in the mind but because CBT can help people manage the pain. A common problem among sufferers is that they think they have harmed themselves so they avoid activity and movement, and become de-conditioned and fearful of pain. They get into a vicious circle which CBT can help to break. An enhanced version of CBT has also shown promising effects in eating disorders by helping tackle problems such as low self-esteem and extreme perfectionism.
What other treatments are there for depression?
Regular exercise boosts self-esteem through improving body image or achieving goals, and by relieving feelings of isolation. It also releases feelgood brain chemicals such as endorphins. Nice says exercise should be combined with cognitive-behavioural therapy as the first line of treatment for mild to moderate depression.
Should we be avoiding antidepressants?
No. Depression can be a serious illness which destroys a person's quality of life and imposes a huge burden on them, their families and society. It causes more deaths, by suicide, than any other psychiatric disorder. In severe cases, drugs can be life-saving. In moderate cases, too, drugs can transform a person's outlook so that they are able to make changes to their life necessary to escape from depression, which seemed impossible while they were depressed. Depression has historically been under-treated and still carries a heavy burden of stigma, which means many people suffer rather than admitting they are ill and seeking treatment.
Is cognitive therapy the answer to depression?