Direct answer
Quick AnswerResearch indicates 50-70% of autistic individuals also meet criteria for ADHD (Attention Deficit Hyperactivity Disorder). In Ontario, both conditions can be diagnosed simultaneously — the DSM-5 removed the previous restriction against dual diagnosis in 2013. An autism + ADHD dual diagnosis qualifies for OAP services. ADHD medication can be prescribed alongside ABA and other autism therapies.
Start with the short answer, then reveal deeper context where helpful.
Autism and ADHD share several features that can make differential diagnosis challenging: difficulty with attention, social challenges, executive function deficits, and sensory sensitivities. Key distinguishing features include the quality of social differences (autism involves qualitative social communication differences; ADHD involves difficulty sustaining attention in social contexts) and the presence of restricted/repetitive interests (more characteristic of autism).
Autism and ADHD share several features that can make differential diagnosis challenging: difficulty with attention, social challenges, executive function deficits, and sensory sensitivities. Key distinguishing features include the quality of social differences (autism involves qualitative social communication differences; ADHD involves difficulty sustaining attention in social contexts) and the presence of restricted/repetitive interests (more characteristic of autism).
A comprehensive assessment by a qualified professional can distinguish between autism-only, ADHD-only, and dual diagnosis. This distinction matters for treatment planning, as each condition benefits from different interventions.
Research
Lai et al. (2019), "Autism and ADHD across the lifespan," The Lancet Psychiatry, 6(8), 677-686
APA
Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), American Psychiatric Association (2013)
A comprehensive autism assessment includes developmental history, standardized testing (ADOS-2, ADI-R), cognitive assessment, and clinical observation.
DSM-5 classifies autism into 3 support levels. Level 1 requires support, Level 2 substantial support, Level 3 very substantial support. Learn the differences.
Girls are diagnosed with autism an average of 1.5 years later than boys. Learn about masking, diagnostic bias, and how to advocate for assessment.
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.
Written by Spencer Carroll
Founder & Autism Advocate
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