There is enough evidence to support the use of CBT,IPT and BA (behavioural activation) in adult depression. It is not clear how much / how long these are required to alleviate depression.Knowing the optimal dose is important in delivering effective services. A metaanalysis by Hansen et al showed that 60% of patients had improved after about 13 sessions. Comparison of shorter vs longer therapies have produced conflicting results. Intensity and frequency of sessions could be as important as total number of sessions.There is very little knowledge about these indicators and their association with the effects of psychotherapies for depression.
Pim Cuijpers Marcus Huibers, David Daniel Ebert Sander L. Koole and Gerhard Andersson examined the association between effectiveness of psychotherapies for adult depression and the treatment factors like number of treatment sessions, duration and frequency.Only RCTs with face-to-face psychological treatment were included.70 studies were included with 92 psychotherapy conditions compared with a control group. 47 of these were on CBT.
Higher number of sessions did not result in more significant benefits.Total contact time was also not significantly associated with outcome. A strong relationship between the number of treatment sessions per week and the effect size was observed.When two instead of one treatment sessions are given per week, without increasing the total number of sessions, the effect size increases with 0.45, which is a moderate effect suggesting that intensity rather than the quantity of psychotherapy determines therapeutic effectiveness.
Authors provide possible explanations for this effect. Animal models have demonstrated that it is the continued survival of neurons ‘‘born’’ within the last five days that is necessary for learning to take place. Another explanation could be that the relationship between client and counselor may develop more rapidly when the contact is more intense.
A small negative association between the duration of the therapy and the effect size was found ,indicating smaller effects when the therapy lasts longer.Though this was not significant in multivariate analysis,authors suggest that time limited therapies may be more effective.
Limitations: quality of studies were not optimal.Quality of therapy was not considered in the analysis.A previous metaanalysis have shown that therapy quality were not strongly related to the effect sizes.None of the studies included were of more than 24 weeks duration.
Conclusion: Number of sessions per week appears to be associated with outcomes rather than duration of therapy.
Summary of the article:
Cuijpers P, Huibers M, Daniel Ebert D, Koole SL, Andersson G. J Affect Disord. 2013 Jul;149(1-3):1-13