+17.6 points average
IQ improvement with ESDM (RCT)
Dawson et al., 2010 — Pediatrics
Before age 3
Optimal intervention window
Multiple meta-analyses; Estes et al., 2015
$187,000-$203,000 USD
Estimated lifetime savings per child
Peters-Scheffer et al., 2012 — Research in Autism Spectrum Disorders
18 and 24 months
Recommended autism screening age
Canadian Paediatric Society, 2019
The Early Start Denver Model (ESDM) is the most extensively studied early intervention for autism in children under 3. A randomized controlled trial by Dawson et al. (2010) demonstrated that children receiving ESDM showed significant improvements in IQ (an average increase of 17.6 points), adaptive behaviour, and autism symptom severity compared to controls. Follow-up studies showed that gains were maintained two years post-intervention.
Naturalistic Developmental Behavioural Interventions (NDBIs) — a class of interventions that includes ESDM, JASPER, and Project ImPACT — are recommended as first-line early intervention approaches by major clinical guidelines. These interventions embed learning opportunities in natural play and daily routines, making them suitable for very young children and implementable by trained parents.
The economic case for early intervention is equally compelling. A cost-benefit analysis by Peters-Scheffer et al. (2012) estimated that intensive early intervention generates lifetime savings of $187,000 to $203,000 (USD) per child through reduced need for special education, residential services, and adult support.
Ontario's early detection ecosystem includes the 18-month well-baby visit screening (using the M-CHAT-R/F), the EarlyAbilities program (speech, occupational, and physiotherapy for children 0-6 through Children's Treatment Centres), and the Ontario Autism Program's Early Childhood Autism Entry Point.
The OAP's early pathway was designed to fast-track children identified before age 2.5 into evidence-based early intervention. In practice, however, waitlists often delay access. Families should simultaneously pursue multiple pathways: request an OAP referral, enroll in EarlyAbilities, explore Infant and Child Development programs through public health, and consider private early intervention services if financially feasible.
Parent-mediated intervention — where a clinician coaches parents to implement therapeutic strategies during daily routines — is strongly supported by evidence and can begin immediately without waiting for formal program placement. Programs like Project ImPACT and the Hanen More Than Words program are available in Ontario through various providers.
Dawson, G. et al.
Randomized, Controlled Trial of an Intervention for Toddlers With Autism: The Early Start Denver Model. Pediatrics, 2010; 125(1):e17-e23
Estes, A. et al.
Long-Term Outcomes of Early Intervention in 6-Year-Old Children With Autism Spectrum Disorder. J American Academy of Child & Adolescent Psychiatry, 2015; 54(7):580-587
Commitment to Accuracy: Our data is verified against official government reports (FAO, MCCSS), peer-reviewed scientific literature, and accessible public records. Last updated: March 24, 2026.
Verified Facts
Early Start Denver Model (ESDM) delivered to children aged 18–30 months produced significant gains in IQ, adaptive behaviour, and autism severity — some children no longer met diagnostic criteria at follow-up
Cochrane systematic review finds evidence that early intensive behavioural intervention (EIBI) may produce positive effects on adaptive behaviour and communication for young children with ASD (low certainty of evidence)
WHO recommends accessible, community-based early interventions for children with autism — timely evidence-based psychosocial interventions improve communication and social engagement
Evidence supports autism screening and intervention commencing in the first 2 years of life — earlier identification directly enables earlier intervention during the highest neural plasticity window
88,175, children are registered in the Ontario Autism Program