Direct answer
Dawson, G. et al. · Estes, A. et al. · Verified 2026-08-10
Quick summary
In brief
Key points
The Evidence for Early Intervention
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 may also be strong. A Dutch cost-benefit analysis (Peters-Scheffer et al., 2012) estimated lifetime savings of approximately €1,103,067 per child, covering ages 3 to 65. This is a European-context model with its own cost assumptions and currency, so the figure should be treated as an illustration of the scale of potential savings, not a direct estimate for Ontario.
Ontario Early Detection and Intervention Pathways
Ontario's early detection options include 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.
Ask about all available early pathways at the same time: Ontario Autism Program registration, EarlyAbilities, Infant and Child Development programs, and private care if affordable. Waits can delay access.
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.
Evidence and sources
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
Frequently asked questions
- Is it too early to start intervention for my 18-month-old?
- No — it is not too early. Research consistently shows that earlier is better. Intervention can begin as soon as developmental concerns are identified, even before a formal autism diagnosis. Parent-mediated early intervention programs can start immediately and have strong evidence for improving outcomes in children under 2.
- Do I need a formal diagnosis before starting early intervention?
- Not for all services. Ontario's EarlyAbilities program and Infant and Child Development programs accept referrals based on developmental concerns, without a formal autism diagnosis. Parent-mediated programs can also begin without a diagnosis. The OAP pathway does require a formal autism diagnosis for core clinical services.
- What can I do while waiting for Ontario services?
- Start parent-mediated strategies immediately: engage in responsive, child-led play; follow your child's interests; narrate activities with simple language; create communication opportunities; and establish predictable routines. Ask your pediatrician for a referral to Infant and Child Development and EarlyAbilities. Hanen's "More Than Words" program is available in many Ontario communities.
Where the waitlist stands
Families navigating autism services in Ontario face a documented multi-year wait. Here is the Ontario data — and a two-minute way to push back, when you are ready.
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