Evidence about ABA treatment for young children with autism

Eric V. Larsson, PhD, LP, BCBA-D, LBA
Lovaas Institute
Association for Science in Autism Treatment

Evidence About ABA Treatment for Young Children with Autism (Council of Autism Service Providers [CASP], 2025) is an important companion to the CASP 2024 Practice Guidelines. This white paper summarizes the evidence from research on early, comprehensive, intensive Applied Behavior Analysis (ABA) treatment, in order to further elaborate the generally accepted standards of care for young children receiving ABA. It also highlights the critical role of treatment intensity on outcomes. In doing so, it provides benchmarks to use to evaluate the outcomes of ABA treatment delivered to young autistic children. These benchmarks can also be applied to evaluate the effectiveness of other treatment approaches offered to this pediatric population.

Overview

Evidence About ABA Treatment for Young Children with Autism (CASP, 2025), is a companion document to the Applied Behavior Analysis Practice Guidelines for the Treatment of Autism Spectrum Disorder (CASP Version 3, 2024). It describes the generally accepted standards for the medically necessary use of ABA to treat the behavior of individuals with autism spectrum disorder (ASD). This white paper summarizes the evidence from research on early, comprehensive, intensive ABA treatment that results in the generally accepted standards of care for young children receiving ABA.

Evidence About ABA Treatment for Young Children with Autism also summarizes a recent meta-analysis of treatment outcomes by Dr. Sigmund Eldevik and colleagues (in press). This paper highlights the critical role of treatment intensity on outcomes. In doing so, it provides benchmarks to use to evaluate the outcomes of ABA treatment delivered to young autistic children. These benchmarks can also be applied to evaluate the effectiveness of other treatment approaches delivered to this pediatric population.

Further, the paper evaluates recent studies in which some authors have claimed that both high and low treatment intensities produce similar outcomes (Ostrovsky et al., 2023; Sandbank et al., 2024). It identifies concerns about the methodology, design and understanding of early intensive intervention for young children with autism in these studies. Finally, it provides resources to help parents and caregivers understand the variables that influence children’s outcomes in early, comprehensive, intensive ABA.

Generally Accepted Standards of Care

Evidence About ABA Treatment for Young Children with Autism provides a review of the concept of “Generally Accepted Standards of Care (GASC).” It discusses how such standards are developed and the legal significance of GASC. It then goes on to show how ABA, as an “Evidence-Based Practice (EBP),” meets the criteria for forming GASC. This paper then provides a detailed summary of how such evidence is evaluated.

Evidence About ABA Treatment for Young Children with Autism provides the Generally Accepted Standards of Care for young children with autism who seek treatment. In brief:

Begin ABA treatment as early as possible.
Treatment should aim to accelerate the child’s developmental trajectories to the greatest extent possible.
For those whose goal is to improve on their developmental trajectory, the focus of treatment would be on increasing the child’s rate of learning.
ABA treatment plans should be comprehensive in scope to address the factors that impede development across all critical domains.

Treatment should target a broad array of behaviors foundational to independent learning (e.g., play, receptive language, imitation skills, attending)
Children should receive an average of 30-40 hours per week of direct intervention for two or more years.
Care should be individualized and provided with a compassionate understanding of the child and family preferences, culture, strengths, and needs.
Parents and other caregivers often make important contributions to the design and provision of treatment for young autistic children throughout all aspects of the intervention.

A crucial characteristic of scientific evidence is that it is replicated. The process of science is to define the treatment parameters and measures sufficiently to enable attempts at independent replication. Once an independent organization produces a credible replication, and an independent group of experts evaluates the overall body of such evidence, the stage is set for consideration of GASC. Therefore, the paper emphasizes the need for multiple studies examining the same parameters and highlights several criteria for evaluating research quality. These criteria include prospective and controlled designs, evaluation within the context of the overall body of research, and conclusions that are logically supported by the methods used. In evaluating the conclusions, the paper recommends adopting an attitude of healthy skepticism and refers the reader to previous articles and reviews of false, misleading, or overstated claims about autism interventions published by the Association for Science in Autism Treatment.

Once a body of studies is available, it is commonly expected that their results will be subjected to credible systematic reviews and meta-analyses. The paper provides a discussion of such methods. The paper proceeds to summarize the evidence that underlies the GASC.

The Relationship Between the Scope of Treatment and Treatment Intensity in Research

Each person who seeks treatment has unique needs and therefore the recommended levels of treatment intensity are varied. Research has been conducted on these different intensities of ABA service delivery, ranging from very comprehensive and intensive to very focused and low intensive. Logically, if the person has a high number of objectives, there is a minimum level of intensity needed just to address each objective. Alternatively, if the treatment objectives are few, lower intensity might be sufficient, dependent upon the nature of the objective. For example, a child may have a high rate of self-injury, and even though the objective is simple, the number of hours needed for treatment may be high before the objective is accomplished. The paper provides a helpful matrix showing the relationship of scope to intensity (Figure 1). In each of these cells, there are valid and meaningful treatment services, yet a well-controlled systematic review would not conflate the cells.

Figure 1

Relationship of Scope and Intensity in ABA Treatment Plans

Because of this, a meaningful meta-analysis requires that the study controls for both the scope and the intensity of treatment. However, the paper offers a review of a meta-analysis that did not control for scope of treatment (Sandbank et al., 2024), and as a result produced conclusions which are not replicated by more adequate systematic reviews and meta-analysis research. The paper describes the Sandbank study as a more extreme example of failure to control for meaningful variables. A review of the citations shows that a substantial number of citations did not adhere to established standards for either ABA or Early Intensive Behavioral Intervention (EIBI) (Maurice et al., 2001), and the majority of those that did were focused ABA studies with widely varying treatment objectives. Finally, the Sandbank study (2024) remarkably failed to include a large number of commonly cited comprehensive ABA studies. Other researchers have since also critiqued the methodology of Sandbank, et al., 2024 (Frazier et al., 2025).

The Results of Well-Controlled Research on the Effects of Intensity

The paper reviews the large body of studies of comprehensive treatment, systematic reviews, and meta-analyses. It then provides a review of the most recent meta-analysis (Eldevik et al., 2024) in detail. This extensive study controlled the scope of treatment to evaluate the effects of three groups of intensities (low, moderate, and high) on outcomes for young children who received comprehensive ABA treatment. It also limited its analysis to studies which adhered to the GASC (CASP, 2024), and to long duration studies, which were better able to measure meaningful outcomes.

This meta-analysis produced a number of results. Figure 2 (graphic is mislabeled) shows the results of the comprehensive treatment of 341 children across three of the measures: Vineland Adaptive Behavior Composite (ABC), IQ, and Childhood Autism Rating Scale (CARS). For each of these measures, the average improvement was consistently related to the average intensity: 5-12 weekly hours, 13-25 weekly hours, or 26-40 weekly hours.

Figure 2 (note that this appears as Figure 3 in the graphic from the original source)

The mean change in standard scores (SS) for adaptive behavior and intellectual functioning, and raw scores of autism severity across three intensity levels of early comprehensive intensive ABA intervention.

This analysis produced similar results with variety of measures. For example, in one of the measures of meaningful improvement – the increase in percentages of persons who scored in the non-clinical range (above a standard score of 85) after high intensity treatment was nearly three times that of the percentage increase after low intensity treatment.

For social validity, it is crucial to look at such measures of meaningful differences, because too often traditional research focuses only on whether a small difference between treatments was at least statistically different. However, genuine social validity depends more on the magnitude and character of the differences (Jacobson and Truax, 1991). In addition to the reported meta-analysis, the paper also provides a review of research on the successful long-term maintenance of treatment gains after intensive treatment.

Based on these results, the paper also establishes benchmarks for progress that parents can use to evaluate their children’s services. For example, by understanding the likelihood of meaningful gains, a parent is better informed to make the important decisions over the many treatment choices being offered to them. These benchmarks thus can enable informed consent. After making the decision to engage in treatment, these standard benchmarks can be used to evaluate the results of their selected treatment.

The paper then goes on to provide a substantial critique of recent papers that purported that the intensity of treatment is not important. The paper describes a study (Ostrovsky et al., 2023) that compared low levels of intensity (less than 10 hours per week) with even lower levels of intensity (less than 7 hours per week). Based on such a minimal difference in treatment, Ostrovsky et al. 2023 still concluded, “The results of the study support the hypothesis that children would have improved outcomes independent of the number of hours of service they received. (p. 6)” The paper noted other critical lapses in research quality, including failure to clearly report the parameters, failure to control for scope of treatment, drawing conclusions from negligible gains, and relying on a retrospective analysis.

Helpful Resources

A special value of Evidence About ABA Treatment for Young Children with Autism (CASP, 2025) are the appendices.

Appendix A provides a sample daily schedule for early comprehensive intensive ABA treatment as designed by the expert panel.
Appendices B, C, and D provide infographics and summaries to use in communicating with parents and caregivers about the GASC for ABA treatment for young children. These are also helpful graphics to incorporate into PowerPoint slide decks for introductory courses.

Evidence About ABA Treatment for Young Children with Autism highlights the critical role of treatment intensity in accomplishing meaningful outcomes. Parents deserve to have the facts to be able to make an informed decision about their child’s care.

References

Council of Autism Service Providers [CASP] (2024). Applied behavior analysis practice guidelines for the treatment of Autism Spectrum Disorder: Guidance for healthcare funders, regulatory bodies, service providers, and consumers [Clinical practice guidelines]. https://www.casproviders.org/asd-guidelines

Council of Autism Service Providers [CASP] (2025). Evidence About ABA Treatment for Young Children with Autism: The Impact of Treatment Intensity on Outcomes. https://www.casproviders.org/evidence-intensive-early-aba

Eldevik, S., Strømgren, B., Eikeseth, S., Field, A., Goetz, C. M., & Titlestad, K. B. (Accepted for publication). Clinically significant outcomes of early intensive behavioral intervention for children with Autism Spectrum Disorders: An individual participant data meta-analysis. Autism Research Journal.

Frazier, T. W., Chetcuti, L., & Uljarevic, M. (2025). Evidence that intervention dosage is associated with better outcomes in autism. JAMA Pediatrics, 179(1), 101–102. https://doi.org/10.1001/jamapediatrics.2024.4710

Jacobson, N. S., & Truax, P. (1991). Clinical significance: A statistical approach to defining meaningful change in psychotherapy research. Journal of Consulting and Clinical Psychology, 59(1), 12–19. https://doi.org/10.1037/0022-006X.59.1.12

Maurice, C., Green, G., & Foxx, R. M. (Eds.). (2001). Making a difference: Behavioral intervention for autism. PRO-ED.

Ostrovsky, A., Willa, M., Cho, T., Strandberg, M., Howard, S., & Davitian, C. (2023). Data-driven, client-centric applied behavior analysis treatment-dose optimization improves functional outcomes. World Journal of Pediatrics, 19(8), 753–760. https://doi.org/10.1007/s12519-022-00643-0

Sandbank, M., Pustejovsky, J. E., Bottema-Beutel, K., Caldwell, N., Feldman, J. I., Crowley LaPoint, S., & Woynaroski, T. (2024). Determining associations between intervention amount and outcomes for young autistic children: A meta-analysis. JAMA pediatrics, 178(8), 763–773. https://doi.org/10.1001/jamapediatrics.2024.1832

CASP Copyright Notice: Electronic and/or paper copies of part or all this work may be made for personal, educational, or policymaking purposes, provided such copies are not made or distributed for profit or commercial advantage. All copies, regardless of medium, must include this note on the first page. Abstracting with proper credit is permitted, so long as the credit reads “Copyright © 2025 by The Council of Autism Service Providers (CASP), all rights reserved.” All other uses and/or distributions in any medium require advance permission of The Council of Autism Service Providers (CASP), available from info@casproviders.org.

Reference for this article:

Larsson, E. (2026). Review of Evidence about ABA Treatment for young children with autism: The impact of treatment intensity on outcomes Science in Autism Treatment, 23(1).

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Review of Evidence About ABA Treatment for Young Children with Autism: The Impact of Treatment Intensity on Outcomes (CASP, 2025)