Mediators of Treatment Outcomes for Anxious Children and Adolescents: The Role of Somatic Symptoms

Cognitive behavioral therapy (CBT) and selective serotonin reuptake inhibitors are effective treatments for pediatric anxiety disorders. However, the mechanisms of these treatments are unknown. Previous research indicated that somatic symptoms are reduced following treatment, but it is unclear if their reductions are merely a consequence of treatment gains. This study examined reductions in somatic symptoms as a potential mediator of the relationship between treatment and anxiety outcomes. Participants were 488 anxious youth ages 7-17 (M = 10.7), 50.4% male, 78.9% Caucasian, enrolled in Child/Adolescent Anxiety Multimodal Study, a large randomized control trial comparing 12-week treatments of CBT, sertraline, a combination of CBT and sertraline, and a pill placebo. Causal mediation models were tested in R using data from baseline, 8-, and 12-week evaluations. Somatic symptoms were assessed using the Panic/Somatic subscale from the Screen for Child Anxiety Related Emotional Disorders. Youth outcomes were assessed using the Pediatric Anxiety Rating Scale and Children's Global Assessment Scale. Reductions in somatic symptoms mediated improvement in anxiety symptoms and global functioning for those in the sertraline-only condition based on parent report. Conditions involving CBT and data based on child reported somatic symptoms did not show a mediation effect. Findings indicate that reductions in somatic symptoms may be a mediator of improvements for treatments including pharmacotherapy and not CBT. Although the overall efficacy of sertraline and CBT for anxiety may be similar, the treatments appear to function via different mechanisms.