Sustained Change in Adoptive Families: A Follow-up Mediation Analysis of Adoption-Specific Therapy (ADAPT) on Behavioral Problems and Attachment in Adopted Children and Parental Stress in Adoptive Parents

Objective This follow-up study had two primary aims: (1) to evaluate the sustainability of effects from Adoption-Specific Therapy (ADAPT) on adopted children’s behavioral problems and attachment security, and on adoptive parents’ stress, three months post-intervention; and (2) to investigate the mechanisms underlying these sustained changes through advanced mediation analysis. Method The study presents secondary analysis of three-month follow-up data from a randomized controlled trial. A sample of 25 Iranian adoptive families (12 in the ADAPT group, 13 in waitlist control) completed assessments at pre-test (T1), post-test (T2), and three-month follow-up (T3). Measures included the Child Behavior Checklist (CBCL), the Kinship Center Attachment Questionnaire (KCAQ), and the Parenting Stress Index-Short Form (PSI-SF). Sustainability was tested using Repeated-Measures MANCOVA. To examine mechanisms, nine parallel and serial mediation models were tested using Hayes’ PROCESS macro, with T3 scores as mediators/outcomes, controlling for baseline scores. Results The RM-MANCOVA revealed a significant and large Group × Time interaction (Pillai’s Trace = .777, *p* = .001). Gains in the ADAPT group on all outcomes were maintained at T3 with no significant decay from T2 to T3, while the control group remained stable. Mediation analyses indicated that ADAPT exerted significant direct effects on all three T3 outcomes (behavior, attachment, stress). However, no single, linear mediation pathway (parallel or serial) was statistically significant. The pattern of results supports a reciprocal, systemic model of change, where improvements in child behavior, attachment security, and parental stress mutually reinforce one another to sustain treatment gains. Conclusion The findings confirm that the benefits of ADAPT are sustained three months after treatment. More importantly, they suggest that its efficacy stems not from a simple causal chain but from initiating a positive, reciprocal cycle of change within the adoptive family system. This underscores the value of integrated, family-system interventions in post-adoption support.