By the age of 19, between a fifth and a quarter of young people have suffered from a depressive disorder. There are associations between depression and self-harm, suicide, substance abuse, poor academic performance and social dysfunction.

The most robust evidence exists for two particular psychological interventions: cognitive behavioural therapy and interpersonal therapy. There is evidence that both are effective treatments for depression and that they may reduce relapse, hence the potential for depression prevention.

Interventions aimed at preventing depression are often delivered in a group setting, both to reduce cost and because a group may reinforce effectiveness by providing positive peer experiences. Both group and individual interventions usually take place on a weekly basis and typically last for 10 to 15 sessions.

In this review, the authors included both psychological and educational approaches to preventing depression. The key differentiating point is that educational interventions simply provide information about depression, through lectures or fact sheets, whereas psychological interventions attempt to change how people think, using a variety of different strategies.

The review followed the usual gold standard Cochrane methodology by searching a wide range of databases, conducting citation searching and contacting experts in the field to identify unpublished or very recent research.

They found 53 randomised controlled trials (including 14,406 patients aged 5-19) comparing psychological or educational prevention programmes with placebo or a comparison intervention. All of the studies focused on patients who did not currently meet diagnostic criteria for depression or who were below the clinical range on standardised, validated, and reliable rating scales of depression, or both.

Overall, the quality of the studies was not high. Allocation concealment was unclear in most and there was heterogeneity in the findings. However, the reviewers reported that the persistence of findings suggested that this is real and not a placebo effect.

Here’s what they found:

• The risk of having a depressive disorder post-intervention was reduced:
• immediately compared with no intervention (15 studies; 3115 participants risk difference (RD) -0.09; 95% confidence interval (CI) -0.14 to -0.05; P<0.0003)
• at three to nine months (14 studies; 1842 participants; RD -0.11; 95% CI -0.16 to -0.06)
• and at 12 months (10 studies; 1750 participants; RD -0.06; 95% CI -0.11 to -0.01)
• There was no evidence for continued efficacy at 24 months (eight studies; 2084 participant; RD -0.01; 95% CI -0.04 to 0.03)
• But limited evidence of efficacy at 36 months (two studies; 464 participants; RD -0.10; 95% CI -0.19 to -0.02)

The reviewers concluded:

We found that, compared with no intervention, psychological depression prevention programmes were effective in preventing depression with a number of studies showing a decrease in episodes of depressive illness over a year. There were some problems with the way the studies were done but despite this the results are encouraging. We found data to support both targeted and universal programmes, which is important as universal programmes are likely to be easier to implement. We recommend that further research be undertaken to identify the most effective programmes and to test these in the real world.

Merry SN, Hetrick SE, Cox GR, Brudevold-Iversen T, Bir JJ, McDowell H. Psychological and educational interventions for preventing depression in children and adolescents. Cochrane Database of Systematic Reviews 2011, Issue 12. Art. No.: CD003380. DOI: 10.1002/14651858.CD003380.pub3.