Can someone be both autistic and ADHD, and what often gets missed?

Yes, and it is common. Around a third of autistic people are also ADHD, and many people are both for their whole lives. For a long time this was not officially possible: until 2013, the diagnostic manual did not allow the two to be recognised together, so a generation of people were given one label and assessed no further. The combination is common enough to have its own community name, AuDHD. What most often gets missed is the second of the two, because being autistic and being ADHD can pull in opposite directions and partly hide each other, and because once someone has one diagnosis, clinicians frequently stop looking for anything else. If you recognise yourself in both, that is not a contradiction. It is a recognised, and fairly common, way of being.

Written and reviewed by Matthew Hallam, Registered Psychologist (AHPRA PSY0002471369). 4 min read. Published 24 May 2026. Last reviewed 24 May 2026. Next review 24 May 2027.

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Why it was treated as either-or for so long

The question itself carries an old assumption, that autistic and ADHD are alternatives, and that being one tends to rule out the other. There is a historical reason for that assumption. Until 2013, the diagnostic manual explicitly prohibited diagnosing both at once. If a person was identified as autistic, ADHD was not considered, by rule rather than by evidence (American Psychiatric Association, 2013).

That rule has gone, and the research that followed it has been clear. Around 37 percent of autistic people are also ADHD, far above the rate in the general population (Micai et al., 2023). The two go together often enough that clinicians increasingly treat the combination as one of the common presentations, not a rare exception. But the assumption left a long shadow. Many adults assessed before 2013, or assessed by someone still working from the older frame, were given one explanation when two were warranted.

Why each one hides the other

The harder reason the second goes unrecognised is that being autistic and being ADHD can pull against each other, and the pull can flatten the picture.

Some of the traits point in opposite directions. ADHD often brings a pull toward novelty, change, and stimulation. Autism often brings a preference for routine, predictability, and sameness. When someone is both, they can look, from the outside, oddly contradictory: craving stimulation and overwhelmed by it, seeking change and undone by it, drawn to spontaneity and reliant on structure. A clinician expecting a clean version of either profile may see neither clearly, because each is muddying the other.

Other traits overlap so closely that they get attributed to whichever label has already been given. Difficulty with attention, with regulating emotion, with managing transitions, with social situations: these can come from being ADHD, from being autistic, or from both, and once one diagnosis is in place, the same trait tends to get filed under it. The clinical name for this is diagnostic overshadowing, where an existing diagnosis absorbs everything and stops the search for anything alongside it (Australian ADHD Professionals Association, 2022).

What this means if you suspect both

If you already have one diagnosis and have always felt it explained most of you but not all of you, that experience is worth taking seriously. The part the first label did not quite cover is exactly the part worth asking about. It does not mean the first diagnosis was wrong. It means it may have been incomplete.

A good assessment for this looks at the whole picture rather than stopping at the first match. That matters practically, because what helps one part of the profile is not always what helps the other, and a plan built around only half of what is going on tends to leave the other half unaddressed.

Being autistic and being ADHD are not alternatives, and they were only ever treated as such by a rule that no longer exists. They go together often, they can disguise one another, and the second is missed far more often than the first. If you see yourself in both, that is not confusion on your part. It is frequently the more complete description, and it is worth bringing to someone who will look at all of it.

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