Evidence About ABA Treatment for Young Children with Autism: The Impact of Treatment Intensity

Evidence About ABA Treatment for Young Children with Autism: The Impact of Treatment Intensity on Outcomes by the Council of Autism Service Providers 

Linda LeBlanc, Ph.D., BCBA-D & Jane Howard, Ph.D., BCBA-D 

In the spring of 2025, the Council of Autism Service Providers (CASP) published a white paper on the impact of treatment intensity on outcomes for comprehensive model ABA treatment for young children with autism.  

The white paper emphasizes the importance of evidence-based practice and the need to provide accurate, scientifically grounded information to families regarding ABA treatment for young children with autism. It provides generally accepted standards of care for this patient population, a summary of the evidence for the effects of treatment intensity, benchmarks for expected treatment effects, and guidance for evaluating studies.  It also includes an analysis of two recently published articles that contest the importance of treatment intensity. Additionally, it contains user-friendly resources for clinicians to share with caregivers that describe the GASC and the related scientific evidence about ABA treatment for young autistic children. 

Generally Accepted Standards of Care (GASC) 

As noted by the National Academies of Science, Engineering, and Medicine in their report on the Autism Demonstration Project for military families (2025), generally accepted standards of care (GASC) are best practice guidelines for serving patients with a specific condition and are widely accepted by professionals in the relevant clinical specialty. They are developed and revised periodically by subject matter experts within that profession, who typically base these standards on reviews and analyses of the relevant scientific research and the consensus of clinicians who serve that patient population. 

Generally accepted standards of care (GASC) are best practice guidelines for serving patients with a specific condition, widely accepted by professionals in the relevant clinical specialty. 

Adherence to GASC is crucial for legal and clinical accountability in providing care. The CASP guidelines for ABA treatment are highlighted as the current standards for behavioral treatment of individuals with ASD. Additionally, the white paper articulates specific GASC for ABA treatment of young children with autism, emphasizing the importance of early intervention and individualized care. These guidelines further underscore the necessity of assessments, treatment planning and delivery, and outcome measures that reflect both the needs of the individual patient and the heterogeneity of the patient populations who benefit from ABA treatment. The GASC for young children receiving ABA treatment are as follows: 

• Begin ABA treatment as early as possible to leverage brain plasticity. 

• Treatment should aim to accelerate the child’s developmental trajectories to enhance their current and future functioning across environments (e.g., home, community, school). 

• Learning rates may need to be higher than typically developing peers for some time to close developmental gaps. 

• ABA treatment plans should be comprehensive in scope. 

• Treatment should target a broad array of behaviors foundational to independent learning (i.e., learning-to-learn repertoires), health, safety, and long-term well-being 

• Aim for 30-40 hours of direct intervention per week for at least two years. ​ 

• Care should be individualized and provided with a compassionate understanding of patient and family preferences, and strengths. 

• Involve parents and caregivers in the treatment process while ensuring access to services is not conditional on their participation.  

Relationship Between Scope and Intensity of Treatment 

The relationship between the scope of treatment (i.e., the breadth and depth of goals) and treatment intensity (i.e., the weekly hours of direct service delivery) described in the CASP (2024) guidelines highlights how essential treatment intensity is for achieving desired outcomes in comprehensive programming for young children with autism. The white paper reviews the body of research that consistently show that higher treatment intensity in comprehensive ABA is linked to better outcomes than low-intensity ABA or eclectic model treatments for young children with autism.  

• Comprehensive treatment necessitates higher intensity to address multiple developmental domains effectively.​ 

• Higher treatment intensity is generally defined as 30-40 hours of direct treatment per week. 

• Focused treatments may require lower intensity, but might still require high intensity for severe challenging behavior. ​ 

• Comprehensive, high-intensity ABA treatment leads to better developmental outcomes and larger improvements in skills such as communication, cognition, and adaptive behavior than ABA treatment provided at lower intensity. ​ 

The Evidence for Treatment Intensity and Outcomes 

This evidence base began decades ago and has expanded significantly. Numerous studies and systematic reviews have analyzed the effects of many variables (e.g., age at start of treatment, treatment intensity, treatment model, supervision variables, level of functioning at the start of treatment) on outcomes for these children. Higher treatment intensity and earlier age at the start of intervention correlate with better long-term outcomes. In addition, the benefits of early comprehensive intensive ABA treatment have been maintained over time in multiple follow-up studies.  

Findings from Eldevik et al. (2024) and Benchmarks for Services 

Eldevik et al. (2024) conducted an analysis of individual outcomes from studies examining the impact of treatment intensity on outcomes for young children receiving comprehensive ABA. ​Outcomes were examined as observed changes in standardized scores (i.e., change scores) as well as the percentage of children scoring in the non-clinical range post-intervention. ​Their findings highlight the importance of treatment intensity in achieving better outcomes. 

• Data analyzed from 341 children receiving varying intensities of ABA treatment. ​ 

• Children were divided into three groups based on treatment intensity: low (5-12 hours), moderate (13-25 hours), and high (26-40 hours). ​ 

• Improvements in cognitive functioning, adaptive behavior, and autism severity were consistent with a dose-response relation (i.e., low-intensity made the least gains, moderate intensity made somewhat higher gains; high-intensity made the greatest gains) 

• ​Some children achieve clinically meaningful gains without reaching the non-clinical range on standardized assessments.  

Higher treatment intensity in comprehensive ABA is linked to better outcomes than low-intensity ABA or eclectic model treatments for young children with autism.  

Eldevik et al. (2024) also proposed benchmarks for evaluating autism interventions based on their findings. These benchmarks provide expected change scores and percentages of children scoring in the non-clinical range at three different levels of intensity for three different outcome measures. These benchmarks can guide provider organizations, clinicians, and parents in evaluating expectations for outcomes. ​Benchmarks should be applied cautiously, ideally to larger groups of children rather than at the individual level. 

Evaluating Research in ABA Treatment 

The document outlines a framework for evaluating research studies related to ABA treatment, emphasizing the importance of methodological rigor and replication in establishing credible evidence. ​Studies should be evaluated with respect to (a) the design of the study, with prospective studies preferred over retrospective studies, (b) the control conditions that are employed in the study, and (c) the degree to which the conclusions are proportional to the quality and strength of the evidence. 

The white paper provides critiques of two recently published studies that claim low and high treatment intensities yield similar results, Ostrovsky et al. (2023) and Sandbank et al. (2024). Concerns about each study are described in relation to the framework described above and how these concerns limit the confidence that we should have in their findings. Many other concerns are described in the white paper, but examples of the concerns are provided below. 

• Ostrovsky et al. included older participants and did not differentiate between comprehensive and focused ABA treatments (i.e., their evaluation was not limited to early and comprehensive treatment). ​In addition, this retrospective analysis included primarily low-intensity treatment based on what was found in the clinical record rather than prospectively examining the full range of treatment intensity. 

• The meta-analysis by Sandbank et al.​ combined studies of focused and comprehensive interventions and left out important controlled comparison studies that should have been included.