Autism intervention meta-analysis of early childhood studies (Project AIM): updated systematic review and secondary analysis.

This large review looked at autism interventions for young children under 8 years old. It found that approaches combining developmental and behavioral methods work best, particularly for improving social communication and core autism challenges. Traditional behavioral methods helped with challenging behaviors, and technology-based programs showed promise for social skills. However, most studies had quality issues, and researchers rarely tracked negative effects, making it hard to fully understand intervention safety.

This comprehensive meta-analysis examined 252 studies involving 13,304 participants to evaluate early autism interventions for children under 8 years. The review found that naturalistic developmental behavioral interventions showed the most robust evidence, improving social communication and autism diagnostic characteristics even when controlling for bias and measurement methods. Developmental interventions also demonstrated benefits for social communication. Behavioral interventions improved challenging behaviors and social-emotional functioning, while technology-based interventions showed promise for specific social skills.

However, the strength of evidence varied considerably depending on study quality, measurement methods, and bias risk. Notably, adverse effects were poorly monitored across studies, limiting comprehensive risk-benefit assessments.

Naturalistic developmental behavioral interventions appear most promising for comprehensive autism support in early childhood. Clinicians should prioritize evidence-based approaches while carefully monitoring for adverse effects. The field needs higher quality studies with objective outcome measures and systematic adverse event tracking.

Many studies had high risk of bias, relied heavily on caregiver reports rather than objective measures, and poorly monitored adverse effects. Effect sizes often diminished when methodological quality controls were applied, suggesting some findings may be overestimated.

To summarize the breadth and quality of evidence supporting commonly recommended early childhood autism interventions and their estimated effects on developmental outcomes. Updated systematic review and meta-analysis (autism intervention meta-analysis; Project AIM). A search was conducted in November 2021 (updating a search done in November 2017) of the following databases and registers: Academic Search Complete, CINAHL Plus with full text, Education Source, Educational Administration Abstracts, ERIC, Medline, ProQuest Dissertations and Theses, PsycINFO, Psychology and Behavioral Sciences Collection, and SocINDEX with full text,, and ClinicalTrials.gov. Any controlled group study testing the effects of any non-pharmacological intervention on any outcome in young autistic children younger than 8 years.

Newly identified studies were integrated into the previous dataset and were coded for participant, intervention, and outcome characteristics. Interventions were categorized by type of approach (such as behavioral, developmental, naturalistic developmental behavioral intervention, and technology based), and outcomes were categorized by domain (such as social communication, adaptive behavior, play, and language). Risks of bias were evaluated following guidance from Cochrane. Effects were estimated for all intervention and outcome types with sufficient contributing data, stratified by risk of bias, using robust variance estimation to account for intercorrelation of effects within studies and subgroups.

The search yielded 289 reports of 252 studies, representing 13 304 participants and effects for 3291 outcomes. When contributing effects were restricted to those from randomized controlled trials, significant summary effects were estimated for behavioral interventions on social emotional or challenging behavior outcomes (Hedges' g=0.58, 95% confidence interval 0.11 to 1.06; P=0.02), developmental interventions on social communication (0.28, 0.12 to 0.44; P=0.003); naturalistic developmental behavioral interventions on adaptive behavior (0.23, 0.02 to 0.43; P=0.03), language (0.16, 0.01 to 0.31; P=0.04), play (0.19, 0.02 to 0.36; P=0.03), social communication (0.35, 0.23 to 0.47; P<0.001), and measures of diagnostic characteristics of autism (0.38, 0.17 to 0.59; P=0.002); and technology based interventions on social communication (0.33, 0.02 to 0.64; P=0.04) and social emotional or challenging behavior outcomes (0.57, 0.04 to 1.09; P=0.04). When effects were further restricted to exclude caregiver or teacher report outcomes, significant effects were estimated only for developmental interventions on social communication (0.31, 0.13 to 0.49; P=0.003) and naturalistic developmental behavioral interventions on social communication (0.36, 0.23 to 0.49; P<0.001) and measures of diagnostic characteristics of autism (0.44, 0.20 to 0.68; P=0.002). When effects were then restricted to exclude those at high risk of detection bias, only one significant summary effect was estimated-naturalistic developmental behavioral interventions on measures of diagnostic characteristics of autism (0.30, 0.03 to 0.57; P=0.03).

Adverse events were poorly monitored, but possibly common. The available evidence on interventions to support young autistic children has approximately doubled in four years. Some evidence from randomized controlled trials shows that behavioral interventions improve caregiver perception of challenging behavior and child social emotional functioning, and that technology based interventions support proximal improvements in specific social communication and social emotional skills. Evidence also shows that developmental interventions improve social communication in interactions with caregivers, and naturalistic developmental behavioral interventions improve core challenges associated with autism, particularly difficulties with social communication.

However, potential benefits of these interventions cannot be weighed against the potential for adverse effects owing to inadequate monitoring and reporting.