The effects of psychotherapeutic approaches in children and adolescents with intellectual disabilities and psychological disorders: a meta-analysis

Children and adolescents with intellectual disabilities (ID) are two to three times more likely to develop mental disorders, with prevalence rates up to 40%. While meta-analyses demonstrate the efficacy of psychotherapeutic interventions in adults, the evidence base for younger populations remains limited. A systematic literature search was conducted across seven databases following PRISMA guidelines. Studies were included if they examined psychotherapeutic interventions for participants aged 3–21 years with borderline intellectual functioning to severe ID (IQ 20–84) and reported quantitative outcomes. The analysis of 16 studies showed a small but significant effect on behavioural disorders across 14 controlled trials (SMD = -0.26, p = .03; I² = 30%). Severity of ID did not moderate outcomes, but individually delivered interventions were more effective (SMD = -0.46) than group-based formats. No effect was found for parental stress (SMD = -0.10, p = .27; I² = 0%). Evidence for internalising disorders came only from a few uncontrolled studies, suggesting large but unreliable effects. Psychotherapeutic interventions thus offered modest benefits for behavioural problems in youth with ID, while clear gaps remain for parental stress and internalizing conditions.