AuDHD is the shorthand for having both autism and ADHD. Depending on which study you trust, somewhere between about 28% and 40% of autistic people also have ADHD, and the spread is not a mistake: the studies counted different people in different ways. Here is what the main sources say, side by side.
A combination that was not allowed until 2013
According to psychologist Tamara May of Monash University writing in The Conversation, the DSM-5 in 2013 was the first edition to allow autism and ADHD to be diagnosed in the same person. Before that, people were often given whichever diagnosis looked more prominent, and much of the earlier research did not consider the two together. That may be part of why the numbers are still being sorted out.
How common is the overlap? The numbers side by side
Lai and colleagues, Lancet Psychiatry, 2019. This meta-analysis pooled 96 studies and found about 28% of autistic people have ADHD, the most common of the mental health conditions analysed (reported by The Transmitter). It only counted studies with at least 20 autistic participants that used DSM or ICD diagnostic criteria, and it left out studies that asked about lifetime diagnoses.
Rong and colleagues, Research in Autism Spectrum Disorders, 2021. This meta-analysis included 63 articles and reported a current prevalence of 38.5% (95% confidence interval 34.0 to 43.2) and a lifetime prevalence of 40.2% (34.9 to 45.7). The authors found age, intellectual disability, recruitment settings and diagnostic criteria all significantly influenced the current figure (abstract).
May, The Conversation, 2024. Her overview says about 40% of people with ADHD also meet the criteria for autism, and vice versa, and that having traits of one without meeting full criteria for the other is more common, possibly around 80%. She cites journal studies for these figures without naming them in the text; treat them as her summary of those studies.
So why 28% in one place and 38.5% in another? The two meta-analyses pooled different sets of studies. Lai’s applied the strict inclusion rules listed above, and Rong’s own paper says recruitment setting and diagnostic criteria moved the result. None of that makes either number wrong. It means “how common is AuDHD” does not have one clean answer yet, and anyone quoting a single figure without a source is rounding off a disagreement.
Reading the percentages without fooling yourself
For scale, May gives autism as affecting about 1% to 4% of the population, and ADHD as affecting about 5 to 8% of children and adolescents and 2 to 6% of adults. The overlap percentages answer a narrower question than most readers are asking. They describe how many people who have one condition also have the other. They do not say how likely you are to have both because you recognise a few traits in yourself.
That is why the roughly 80% figure for shared traits needs care. Having some autistic traits without meeting the criteria for autism, or some ADHD traits without meeting the criteria for ADHD, is not a diagnosis of either. It is not a reason to label yourself, and if it worries you, a health professional is the person to ask.
Why the two sets of needs can collide
May’s account of how this can feel in practice is careful about its own limits: she notes there is little research on the lived experience, though clinical observations exist. Autistic people generally prefer order and one task at a time, she writes, while people with ADHD often struggle to keep things organised and often have many things on the go. Put both in one person and you can get cycles of organising and falling apart, with distress in between. Overstimulation is associated with autism and understimulation with ADHD, so the two can pull in opposite directions, though some people find a middle ground. She adds that special interests may be shorter-lived, or look more like ADHD-style deep dives.
Mental health, and what the support picture looks like
May’s own research found children with AuDHD have more mental health difficulties than children with autism or ADHD alone, and she points to other studies linking AuDHD to more depression, more anxiety and more difficulty with everyday functioning. She attributes this to an additive effect of the executive function difficulties (planning, organising, attention, impulse control) found in both conditions.
On treatment, her overview says ADHD medications are evidence-based, and that studies suggest they help ADHD symptoms in autistic people in a similar way, but they do not reduce autistic traits, so other support may still be needed. Psychological therapy and occupational therapy are less researched in AuDHD but likely to help, and she lists psychoeducation and psychological therapy as evidence-based treatments. That is one expert’s summary, not medical advice, and any question about medication belongs with a prescriber who knows both conditions.
Is AuDHD an official diagnosis?
May describes AuDHD as having both autism and ADHD, which the DSM-5 lets a clinician diagnose in the same person. None of the sources cited here describes a separate diagnostic category for AuDHD, so treat the word as the name people use for the combination, not as a third condition with its own criteria.
What AuDHD does not tell you
It is not a test, and reading about it cannot confirm anything about you. May recommends that anyone with autism or ADHD consider whether the other is also present and talk it through with a health professional, because people with both may not be identified when they co-occur. If you are at that stage, here is how an autism assessment works and what to expect.
Finally, the exhaustion that comes with juggling both is a theme on this site too. Spoon theory is a workable way to talk about it, and if the load has already tipped over, the guide to burnout recovery while you still have to work is where to go next.
