ADHD and Autism: Understanding the Overlap in the UK
ADHD and autism are not the same condition — but they co-occur in around 30–50% of cases, and they share many surface-level similarities that can make diagnosis confusing. This guide explains the key differences, the overlaps, and what it means if you or your child might have both.
How Common Is ADHD and Autism Together?
Research suggests that approximately:
- 30–50% of autistic people also have ADHD
- 20–50% of people with ADHD also meet criteria for autism spectrum condition (ASC)
Until 2013, the DSM-IV prevented clinicians from diagnosing both conditions simultaneously. The DSM-5 (2013) removed this restriction, recognising the significant overlap. This change has led to a surge in combined diagnoses — not because more people have both, but because it can now be formally recognised.
Key Differences Between ADHD and Autism
| Feature |
ADHD |
Autism |
| Core difficulties |
Attention regulation, impulse control, executive function |
Social communication, restricted/repetitive patterns, sensory processing |
| Social motivation |
Typically want social connection; struggle with social rules due to impulsivity |
May have less intrinsic drive for social interaction; find social rules genuinely confusing |
| Sensory sensitivities |
Can occur but not a core feature |
Very common; often significant |
| Routines and change |
Often resist routine; seek novelty |
Often need routine; distressed by change |
| Hyperactivity |
Common (especially in combined type) |
Less common; stimming may superficially resemble hyperactivity |
| Response to medication |
70–80% respond well to stimulants |
More variable; can worsen anxiety in some autistic people |
Shared Features That Can Cause Confusion
Several features appear in both conditions, making differential diagnosis challenging:
- Executive function difficulties — planning, organising, switching tasks: present in both
- Emotional dysregulation — intense emotional reactions, meltdowns: common in both
- Sensory sensitivities — can be present in both, though usually more prominent in autism
- Social difficulties — for different reasons: ADHD (impulsivity, missing social cues due to inattention) vs autism (genuinely different social processing)
- Sleep difficulties — very common in both
- Anxiety — frequently co-occurs with both conditions
What Does a Combined Assessment Involve?
If you think both ADHD and autism may be present, a combined assessment is more efficient and cost-effective than two separate assessments. It typically involves:
- Longer appointment time (often 2–3 hours)
- Assessment tools for both conditions: DIVA or similar for ADHD; ADOS-2 or similar for autism
- A single comprehensive report covering both conditions
- One set of recommendations covering both diagnosis pathways
Combined assessments typically cost £1,500–£2,800 — less than two separate assessments. Use our free matching service to find providers offering combined assessments in your area.
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Frequently Asked Questions
Can you have both ADHD and autism?
Yes — ADHD and autism co-occur in approximately 30–50% of cases. Until 2013, clinicians were not allowed to diagnose both simultaneously under DSM-IV rules. The DSM-5 removed this restriction, and combined diagnoses are now increasingly common and recognised. Having both is sometimes called ‘AuDHD’.
How do I know if I have ADHD, autism or both?
Only a qualified specialist can determine this through a comprehensive assessment. Key indicators that both may be present include: meeting criteria for inattention/impulsivity AND having consistent difficulties with social communication and/or sensory sensitivities AND restricted/repetitive patterns. A combined assessment is the most efficient way to explore this.
Which should I get assessed for first — ADHD or autism?
Ideally, seek a combined assessment that evaluates both simultaneously. If you must choose, consider which set of difficulties is causing more impact right now — ADHD medication can help if ADHD is confirmed, whereas autism support tends to be more environmental and skills-based. A good assessor will screen for both regardless of the primary referral reason.
Important: Information on this site is for general purposes only and does not constitute medical advice. Always consult a qualified healthcare professional. Assessment details correct at time of publication (May 2026). ADHD Assessment UK may receive a referral fee from providers listed.
