Cognitive Behavior Therapy (CBT) is proving to be one of the most successful and widely applied treatments for child development impairments. Indeed, in some areas of children’s services its popularity amounts to being something of a threat; in the hunt for something that works people increasingly turn to CBT as a potential cure-all.

But like most effective treatments CBT does not work for everything. And we need to know much more than we do at the moment about why it works, for what kinds of problem and under what circumstances.

Some fresh insight is being provided by a group of Japanese scientists from the universities of Miyazaki and Hokkaido led by Shin-ichi Ishikawa who have carried out a meta-analysis of 20 randomized controlled trials of CBT programs for childhood anxiety disorders.

The prevalence of childhood anxiety is often underestimated. Reliable epidemiology indicates that about one in ten children will have an anxiety disorder sufficiently serious to undermine their ability to participate fully in daily life. Ishikawa’s team cast a relatively wide net, including evaluations of CBT for obsessive behavior, school refusals and post traumatic stress disorder.

One of the pitfalls of evaluating programs like CBT is the likelihood of a significant placebo effect: any contact with an expert will generally produce some improvement in a child’s condition.

The Japanese team took this into account when calculating the effects – and still found convincing evidence. CBT retrieves many children from beyond the threshold of a clinical disorder. Since anxiety often produces depression, and vice-versa, so CBT can be shown to have a broad impact on children’s mental health. And the improvement appears to last for up to two years in some studies.

The benefits appear to be much the same for short- and long-term programs, and for those that focus on the individual or rest on group work. So Ishikawa and colleagues draw the obvious conclusion: for the most cost-effective use of CBT with anxiety disorders practitioners should consider working with groups of ten children or fewer.

As with nearly all effective interventions, program fidelity is crucial. The farther practitioners stray from the instruction manual the poorer are the results.

See Queensland assault against anxiety builds on the FEAR plan for a fuller account of how CBT works in the context of childhood anxiety.

• Summary of: Shin-ichi Ishikawa, Isa Okajina, Hirofumi Masouka and Yuji Sakano, “Cognitive Behaviour Therapy for Anxiety Disorders in Children and Adolescents: A Meta-Analysis”, Child and Adolescent Mental Health, 12,4,2007, pp 164 –172