Autism + ADHD Co-occurrence
Why these conditions so often occur together, how they overlap and differ, and how to support children with both.
of autistic individuals also have ADHD
of those with ADHD also have autism
when DSM-5 first allowed dual diagnosis
more likely to have co-occurring conditions
Why do they co-occur?
Until 2013, the DSM prohibited diagnosing both autism and ADHD in the same person. This changed with DSM-5, reflecting what clinicians and families had long observed: these conditions frequently occur together.
Research shows significant genetic overlap between autism and ADHD, suggesting shared biological pathways.
Both conditions involve differences in brain development, connectivity, and neurotransmitter systems.
Better recognition of both conditions means more accurate identification of co-occurrence.
Prenatal factors, prematurity, and family history increase risk for both conditions.
Organisation, planning, working memory, task initiation challenges
Present in both but may manifest differently
Over- or under-responsiveness to sensory input
More commonly associated with autism but also present in ADHD
Difficulty managing emotional responses, meltdowns
Common in both; rejection sensitivity more associated with ADHD
Challenges with peer relationships and social situations
Different underlying mechanisms
Difficulty falling asleep, disrupted sleep architecture
Present in both for different reasons
Ability to deeply focus on preferred activities
Special interests (autism) vs hyperfocus (ADHD)
Key differences and how they combine
Autism
Deep, sustained focus on interests; difficulty shifting attention
ADHD
Variable attention; struggles with sustained attention on non-preferred tasks
Both together
May have both: hyperfocus on interests AND distractibility elsewhere
Autism
May not seek social connection in typical ways; content alone
ADHD
Typically seeks social connection; impulsivity can disrupt relationships
Both together
Complex: may desire connection but struggle with both reading cues AND impulsivity
Autism
Strong need for predictability; distress with unexpected change
ADHD
May seek novelty; can become bored with routine
Both together
May need routine AND crave stimulation simultaneously
Autism
May be literal; misses implied meaning; echolalia possible
ADHD
May interrupt, talk excessively, miss social cues due to inattention
Both together
Both processing differences AND impulsive communication
Autism
Stimming for regulation; repetitive movements
ADHD
Fidgeting due to hyperactivity; constant movement
Both together
May have both stimming AND hyperactive movement
Unique support challenges
Need for routine (autism) vs need for novelty (ADHD)
Stimulants may help ADHD but worsen anxiety common in autism
ADHD impulsivity may mask autistic social differences
Sensory overload + distractibility compound difficulties
Social skills groups may not address both sets of needs
Support strategies for both
- Reduce sensory overwhelm (helps both)
- Provide structure with flexibility
- Visual supports for organisation
- Movement breaks throughout the day
- Clear, concrete instructions
- One instruction at a time
- Check understanding
- Allow processing time
- Teach interoception (body awareness)
- Co-regulation before self-regulation
- Identify triggers for both conditions
- Build in recovery time
- Leverage interests for engagement
- Break tasks into small steps
- Provide frequent feedback
- Allow for movement and fidgeting
AuDHD (autism + ADHD) is not simply additive. When both conditions are present, they interact in complex ways. A child with both may have needs that seem contradictory - craving routine AND novelty, needing stimulation AND quiet. Understanding this complexity is key to effective support. Neither diagnosis fully explains the child; both together create a unique profile.