The aims of this study were to undertake a meta-analytic and systematic appraisal of the literature investigating the effectiveness of cognitive behavioural therapy (CBT) when used with individuals who have autistic spectrum disorders (ASDs) for either a) affective disorders, or b) the symptoms of ASDs. Following a systematic search, 48 studies were included. CBT, used for affective disorders, was associated with a non-significant small to medium effect size, g=0.24, for self-report measures, a significant medium effect size, g=0.66, for informant-report measures, and a significant medium effect size, g=0.73, for clinician-report measures. CBT, used as a treatment for symptoms of ASDs, was associated with a small to medium non-significant effect size, g=0.25, for self-report measures, a significant small to medium effect size, g=0.48, for informant-report measures, a significant medium effect size, g=0.65, for clinician-report measures, and a significant small to medium effect size, g=0.35, for task-based measures. Sensitivity analyses reduced effect size magnitude, with the exception of that based on informant-report measures for the symptoms of ASDs, which increased, g=0.52. Definitive trials are needed to demonstrate that CBT is an empirically validated treatment for use with people who have ASDs.
