Feasibility and Preliminary Efficacy of a Caregiver-Assisted Group-Based Naturalistic Developmental Behavioral Intervention Program for Autistic Preschoolers: A Pilot Randomized Controlled Trial

Naturalistic Developmental Behavioral Interventions (NDBIs) effectively improve developmental, social, and adaptive outcomes in autistic children, with caregiver involvement further enhancing treatment effects. Although one-on-one NDBI programs are strongly supported by evidence, their reliance on high staff-to-child ratios and certified therapists limits scalability. Group-based NDBI models may represent a more feasible and cost-effective alternative, particularly when implemented with open-access fidelity frameworks and active caregiver participation. This pilot randomized controlled trial compared a caregiver-assisted, group-based NDBI program with a therapist-delivered one-on-one NDBI program in autistic children aged 2 to 5 years. Both interventions were administered twice weekly for 12 weeks, with fidelity monitored using the NDBI Fidelity (NDBI-Fi). Forty autistic children were enrolled, and 38 children were included in the final analyses. Both groups showed significant improvements over time in verbal development, social interaction, adaptive functioning, autistic symptoms, problem behaviors, and caregiver stress. A significant time-by-group interaction was observed for nonverbal development, with significant gains in the one-on-one NDBI group but not in the group-based condition. These preliminary findings suggest that a structured, caregiver-assisted group-based NDBI model that integrates caregivers’ assistance, maintains intervention fidelity, and reduces staffing demands is feasible and associated with changes over time, indicating its potential as a scalable intervention approach. Clinical trial registry: https://clinicaltrials.gov/study/NCT06221943 Lay Abstract Early intervention can help young autistic children improve communication, learning, social skills, and daily functioning. One widely used approach, Naturalistic Developmental Behavioral Intervention (NDBI), teaches skills through play and everyday activities, while actively involving caregivers. However, traditional NDBI is typically delivered one-on-one by trained therapists, which can be costly and difficult for many families to access. This study evaluated a new, group-based NDBI program in which small groups of young children and their caregivers learned together with therapist guidance. Thirty-eight autistic children aged 2 to 5 years received two sessions per week over 12 weeks, with 19 receiving the group program and 19 receiving the therapist-delivered one-on-one intervention. Children in both groups showed meaningful improvements in language, social interaction, adaptive functioning, autistic symptoms, and behaviors. Caregivers in both groups also reported feeling less stressed. The group-based model was feasible and acceptable while supporting positive developmental changes. However, significant improvements in nonverbal development were observed only in the one-on-one intervention group. Overall, these findings suggest that caregiver-assisted group-based NDBI is a promising and more accessible early intervention option, especially in settings where individualized therapy is limited or difficult to obtain.