Let me be clear up front, because it matters: I have both. ADHD has been with me a long while, and Autism Spectrum Disorder (ASD) was added at 50 (plus BPD, but that's another story). So this post is part explainer and part me thinking out loud.
What is AuDHD? It's an informal word, used mostly by the people who live it, for being both autistic and ADHD. It's not a separate diagnosis. Since the DSM-5 came out in 2013, a clinician can diagnose both in the same person, which wasn't allowed before. The overlap is big. And the two can work against each other in the same head, which is part of why it gets missed.
How common is it to have both autism and ADHD?
More common than most people think. The UK research charity Autistica, on its ADHD and autism page, says 28% of autistic children meet the criteria for ADHD, and 21% of children with ADHD are also autistic or show heightened autistic traits. It also points to high heritability and genetic overlap between the two.
For a long time, you couldn't officially have both. The old manual, the DSM-IV, didn't allow an ADHD diagnosis if the person was autistic. The DSM-5 dropped that rule in 2013. Spectrum, the autism research news site (now part of The Transmitter), covered the change at the time.
That matters for anyone my age. If you were a kid in the 70s or 80s, the system barely had a word for autism in someone who talked and did fine in school, never mind both at once.
What does AuDHD feel like?
Autistica puts it well. The two share a bunch of traits: sensory differences, intense focus on particular interests, rejection sensitivity, executive dysfunction, sleep problems, emotional dysregulation. Then they split. People with ADHD tend to chase novelty and make impulsive calls. Autistic people tend to crave routine and structure. When you have both, Autistica describes "an internal struggle" between them.
I recognise that tug-of-war. I live with both diagnoses, so here's what it's like for me:
I want the same breakfast and the same chair. Change my routine and I'm rattled for the day. And then, two weeks into a perfectly good routine, I'm bored out of my skull and I've started three new projects. I start things with huge energy and then crash. I've done it my whole life. Big launch, all-nighters, then flat.
Is that ADHD, or autism with burnout cycles and special interests? Both? Honestly, I don't know yet. That's the point of this post. The traits blur together, and from the inside you can't sort them.
Why does AuDHD get missed?
A few reasons, and they stack.
One can hide the other. From what I've read, the autistic need for routine can give an ADHD brain some scaffolding, so the chaos looks smaller. ADHD restlessness and chattiness can make an autistic person look "too social" to be autistic. Each one covers some of the other's tracks.
Masking. If you've spent decades performing normal, you've probably hidden a fair bit of both. I wrote about that in what masking is.
You get answers to the question you walk in with. Go in for autism, you get assessed for autism. Go in for depression, and that's often where it stops.
The old rules. Anyone diagnosed before 2013 couldn't officially get both.
How do you get assessed for ADHD if you're already autistic?
Ask. Specifically. Tell whoever's assessing you that you're autistic and that you want ADHD looked at too.
In Canada, the clinical guidelines most clinicians use come from CADDRA, and they're available in English and French. The Canadian charity CADDAC has a page on adult ADHD that lays out who can diagnose it: family doctors with ADHD training, psychiatrists, psychologists and neurologists. Doctors and psychiatrists are covered by provincial health plans, but waits can be long. Psychologists are faster and cost money.
In Québec, start with your family doctor or your CLSC. Bring examples from childhood if you have them (old report cards help), and if someone who knew you as a kid can weigh in, even better. The NHS notes that ADHD symptoms usually start before age 12, so they'll ask about your history, not just the last few months.
If you want to see what adult ADHD looks like day to day, I wrote about signs of adult ADHD that hide in plain sight.
Is it worth finding out at 50-plus?
For me, getting the diagnoses at 50 was worth it. They gave me a way to understand a whole life. For you, an ADHD answer, yes or no, could do something similar. It could also matter for treatment. Some ADHD supports, including medication, are different from what helps autistic people. That's a conversation for a doctor, not a blog.
If you want one practical book in the meantime, Russell Barkley's Taking Charge of Adult ADHD is dry and no-nonsense, written by one of the most cited ADHD researchers around. He's strongly pro-medication, so keep that in mind.
Taking Charge of Adult ADHD (2nd ed.)
Russell A. Barkley
My take. No fluff. One of the most cited ADHD researchers alive, writing for adults who need tools on Monday morning.
Good to know. Dry, and strongly pro-medication.
And if the boom-then-crash thing is familiar, there's more on that in hyperfocus, then the crash.