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Core Module

Overlaps & Co-occurrence

ADHD and autism frequently co-occur, and many conditions can look similar. Understanding overlaps helps prevent misdiagnosis and ensures appropriate support.

50-70%

of autistic children also meet criteria for ADHD

20-50%

of children with ADHD show autistic traits

3+ years

average delay to correct diagnosis when both present

Why this matters

Until 2013, clinical guidelines prevented diagnosing both autism and ADHD together. This led to generations of children receiving only partial diagnoses.

Today we know co-occurrence is common, but assessment practices haven't always caught up. Many children still receive one diagnosis when they have both, or are misdiagnosed with anxiety or behavioural problems.

Understanding overlaps helps you advocate for comprehensive assessment and ensure your child gets the full picture.

Quick comparison: ADHD vs Autism vs Both
FeatureADHDAutismBoth
AttentionVariable, interest-dependentDeep focus on interestsHighly variable, complex
SocialImpulsive, may interruptDifferences in social cognitionBoth patterns present
FlexibilityImpulsive shiftsPrefers routine, resists changeContradictory - rigid yet impulsive
SensorySeeking stimulationOver/under-sensitivityComplex sensory profile