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ADHD and autism together: what you need to know
ADHD and autism are distinct neurodevelopmental conditions, but they can occur in the same person.
Some experiences may appear similar from the outside, while the processes behind them and the support needed may differ.
A screening test cannot diagnose ADHD or autism. A comprehensive assessment considers developmental history, everyday functioning and other possible explanations.
ADHD and autism occur together relatively often. A 2021 review combined the findings of 63 studies. It found that approximately four in ten autistic participants also met the diagnostic criteria for ADHD. Autism-related features may also be more common among people with ADHD, but having these features is not the same as receiving an autism diagnosis. There is no single figure that applies to everyone. Studies have included people of different ages and backgrounds, and the settings and methods used have also varied.
What do AuDHD prevalence estimates mean?
A screening score is not the same as a confirmed diagnosis.
An estimate from one study may not apply equally to every group of people.
ADHD does not automatically mean that autism is present, nor does autism alone mean that ADHD is present.
ADHD and autism are not the same, although some of their features may appear similar. An autistic person may enjoy new experiences, and a person with ADHD may rely heavily on routines.
The following table shows possible patterns rather than diagnostic rules.
How ADHD and autism may differ
When both are present
Further assessment may be helpful if:
you already have an ADHD or autism diagnosis, but it does not explain all of your experiences;
ADHD-related difficulties have been present since childhood;
autism-related features have also been present over time;
both sets of needs appear together;
these patterns occur across different areas of life;
maintaining everyday functioning requires considerable energy.
You do not need to decide in advance which diagnosis is “correct”. The purpose of assessment is to understand the full picture, not to confirm a conclusion chosen beforehand.
What should an assessment clarify?
A thorough assessment considers both what a person does and what may be contributing to it. The clinician explores:
How does the person experience the situation?
How long have these experiences been present?
In which situations do they occur?
What makes them more or less noticeable?
How do they affect everyday life and wellbeing?
The assessment helps clarify whether ADHD, autism, both conditions or another explanation best accounts for the difficulties.
How does an ADHD assessment work? →
Our free five-minute ADHD screener may provide a useful indication and some preliminary information. A screener is not a diagnosis and cannot replace consultation with a suitably qualified health professional.
Ready to learn more about ADHD assessment?
Connect with a suitably qualified health professional who can help you explore what may be contributing to your experiences and whether a full ADHD assessment could be helpful.
Types of ADHD: how can they look different?
Not sure how the different ADHD presentations may appear in everyday life? Learn more about types of ADHD, how they vary between people, and when further assessment may be worth considering.
Types of ADHD →
Explore the essentials
This page is the starting point for the full ADHD series. Each of the following articles explores one part of the topic in more detail.
Understanding the essentials
Assessment
This page provides general information only.
It cannot determine whether you have ADHD and it does not replace a full assessment by a suitably qualified health professional with training and experience in ADHD.
Australian ADHD Professionals Association, 2022. Australian evidence-based clinical practice guideline for attention deficit hyperactivity disorder (ADHD). https://adhdguideline.aadpa.com.au/
New Zealand Ministry of Health, 2025. New Zealand clinical principles framework for attention deficit hyperactivity disorder. https://www.health.govt.nz/publications/new-zealand-clinical-principles-framework-for-attention-deficit-hyperactivity-disorder
National Institute for Health and Care Excellence, 2018 (updated 2019, reviewed 2025). Attention deficit hyperactivity disorder: Diagnosis and management (NICE Guideline NG87). https://www.nice.org.uk/guidance/ng87
Centers for Disease Control and Prevention, 2026. ADHD in adults. https://www.cdc.gov/adhd/about/adhd-in-adults.html
CADDRA – Canadian ADHD Resource Alliance, 2020. Canadian ADHD practice guidelines (4.1 ed.). https://www.caddra.ca/canadian-adhd-practice-guidelines
Rong, Y., Yang, C.-J., Jin, Y., & Wang, Y., 2021. Prevalence of attention-deficit/hyperactivity disorder in individuals with autism spectrum disorder: A meta-analysis. Research in Autism Spectrum Disorders, 83, Article 101759. https://doi.org/10.1016/j.rasd.2021.101759