Diagnosing Autism in People with ADHD
Understanding the Overlap — and the Differences
Autism and ADHD frequently co-occur, and their overlapping characteristics can make accurate diagnosis complex—but not impossible. At Affirming Autism, we specialise in recognising how these neurodevelopmental conditions interact and how autism may be missed or misunderstood in individuals already diagnosed with (or suspected to have) ADHD.
Autism & ADHD: A Common but Often Overlooked Co-occurrence
It’s estimated that up to 50–70% of autistic people also meet criteria for ADHD. Despite this, many adults are given an ADHD diagnosis without being assessed for autism—particularly if they present as articulate, high-achieving, or appear "social enough" on the surface.
Over time, they may begin to notice that ADHD doesn’t fully explain their sensory sensitivities, social difficulties, or intense need for routine and predictability.
Shared Characteristics — and Why They Can Be Confusing
Autism and ADHD share several features, including:
- Executive function challenges (e.g. difficulties with organisation, memory, and planning)
- Focus differences (e.g. hyperfocus, distractibility)
- Emotional sensitivity and regulation difficulties
- Social communication challenges
But there are also key differences. For example:
Autistic people may crave routine, predictability, and sensory control, and often struggle with unspoken social rules.
People with ADHD tend to seek novelty and stimulation, and their social challenges are often due to impulsivity or inattention, rather than confusion about social convention.
Why Autism Can Be Missed in People with ADHD
Because ADHD characteristics are more widely recognised and socially accepted, many people are identified with ADHD first—and may even mask or misunderstand their autistic characteristics as "just ADHD". Clinicians may also focus on ADHD symptoms without exploring deeper neurodevelopmental differences.
Some autistic adults with ADHD report feeling:
- Misunderstood or partially explained by their ADHD diagnosis
- Overwhelmed by sensory input, routines, or social expectations
- Confused about their persistent difficulties with identity, communication, or self-understanding
Our Diagnostic Approach
At Affirming Autism, we:
- Recognise and validate the overlap between ADHD and autism
- Take time to differentiate between similar behaviours with different underlying causes
- Use a neurodiversity-affirming, trauma-informed framework that avoids pathologising natural ways of thinking and being
Whether you have a formal ADHD diagnosis or simply suspect you might be neurodivergent, we’re here to help you understand the whole picture—with compassion, clarity, and care