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Question In patients with mild to moderate depression, is cognitive therapy (CT) an effective treatment?
Studies were identified by searching Medline and EMBASE/Excerpta Medica; scanning the bibliographies of identified papers and books; referring to previous reviews; reviewing the abstracts from congress presentations; and preprints sent by authors.
Studies were selected if they were randomised controlled trials with ≥1 CT group and 1 comparison group (waiting list, placebo, antidepressants, behaviour therapy, or another psychotherapeutic treatment) in patients who had major depression or dysthymic disorder, with the exclusion of psychotic depression and bipolar affective disorder.
Data were extracted on patient characteristics, treatment conditions, and severity of depression after treatment measured using the Beck Depression Inventory (BDI).
78 trials were identified of which 48, including 2765 patients, met the selection criteria. In the 20 studies that compared CT with waiting list or placebo, the average patient in the CT group was 29% better than the average patient in the control group after treatment (effect size 0.82, p<0.001). In the 17 trials that compared CT with antidepressants, the average patient in the CT group was 15% better than the average patient in the antidepressant group after treatment (effect size 0.38, p<0.001). In the 22 trials that compared CT with a group of miscellaneous therapies (including psychodynamic therapies, interpersonal therapies, non-directive, supportive, relaxation, and alternative bibliotherapy), the average patient in the CT group was 10% better than the average patient in the other therapies group after treatment (effect size 0.24, p<0.01). There was no significant heterogeneity* in the results of studies comparing CT v antidepressants, or CT v other therapies. In the 13 trials that compared CT with behaviour therapy, no difference existed between groups (effect size 0.05, p=0.95), but there was evidence of significant heterogeneity* between studies (p<0.001). In multiple regression analysis, after adjustment for type of treatment, no association was found between the effect size and BDI score, sex, and age. In the 8 trials that allowed a comparison of CT with antidepressants at 1 year follow up, 5 of the 8 studies suggested a preventive effect of CT on relapse rate.
In patients with mild to moderate depression, cognitive therapy has a beneficial effect equivalent to that of behaviour therapy and that of antidepressants and a group of other miscellaneous therapies.
The conclusion about the efficacy of CT for depression is no longer tentative. For mild to moderate depression, it may even be the treatment of choice. Scientific evaluation of the effectiveness of different modes of treatment is welcome news for the clinician. This is especially meaningful when emerging conventional clinical wisdom is supported by research. Clinicians seem comfortable with the conclusion that for mild to moderate depression patients can be offered the choice of short term therapy (cognitive or behavioural) or medication. This review by Gloaguen et al supports those who believe that cognitive behavioural therapy should be the treatment of first choice for depression.1
The comparison of CT with behaviour therapy and other psychotherapies leads the reader to the “specific, non-specific” factors debate of what is central to therapeutic change.2 This debate has recently been discussed by Oei and Shuttlewood in the area of CT for depression and remains a controversial issue.3 The suggestion that “cognitive modification” is the specific factor in the treatment of depression was not supported by the analysis by Gloaguen et al. This was attributed to the use of a number of similar strategies by both CT and behaviour therapy.
An additional point of interest in this review is the suggestion of a preventive effect of CT on relapse rate. The possibility that treating depression with CT or behaviour therapy may reduce the risk of relapse or perhaps the need for further treatment is considered by some to be one of the most exciting outcomes of research in this area because recurrence of depressive episodes is not uncommon after successful treatment.4
Source of funding: no external funding.
For correspondence: Dr J Cottraux, Anxiety Disorder Unit, Hopital Neurologique, 59 boulevard Pinel, 69394 Lyon, France. Fax +33 723 57330.
Abstract and commentary also published in Evidence-Based Medicine.
↵* Heterogeneity means that there is greater variation in the results of the trials than would be expected by chance variation alone, and the pooled estimate must be interpreted with caution.
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