Efficacy and effectiveness of parent training program as a transdiagnostic intervention: A meta-analysis of its impact on internalizing and externalizing problems in children.

Parent training programs (PTPs) aim to improve parenting skills and reduce children's behavioral and emotional problems. Given that recent research has extended PTPs' application from externalizing difficulties to internalizing symptoms - problem domains that frequently overlap in children - evaluating their effects together can clarify PTPs' broader impact. This meta-analysis synthesized findings from 34 randomized controlled trials involving children aged 3-12 years to examine the efficacy of PTPs and identify factors influencing treatment outcomes. Across studies, PTPs significantly reduced both internalizing (g = 0.28) and externalizing (g = 0.37) problems, yielding effect sizes comparable to those reported in prior parent training research. Importantly, PTPs also demonstrated significant cross-domain effects, indicating that programs targeting externalizing problems may also reduce internalizing problems, and vice versa. Moderator analyses indicated that only children's clinical diagnoses significantly predicted externalizing outcomes. These findings suggest that PTPs may be implemented flexibly across varying delivery conditions. Despite small overall effects, heterogeneity, and publication bias, the findings support the effectiveness and adaptability of PTPs. Future research should employ mechanism-informed, scalable designs to enhance accessibility and optimize treatment efficiency.