This may be incredibly offensive, but how big could a potential overlap be between ADHD and autism?

Pretty big. The key word is "comorbidity"; having one of them means you are more likely to have the other than a random person.

There's also an overlap in traits.

I'm AuDHD (autism + ADHD). You can read about my ADHD side if the experience (with memes!) here:

https://romankogan.net/adhd

It's not clear how distinctive a lot of mental health conditions are. For the most part we're just making up labels for groups of signs and symptoms, after all. To the extent the labels are "real" things mostly rests in their utility—I mean, that's sort of true of all labels for everything (what's a chair?) but these are far more fluid than most.

It could be that autism really is, exactly as we describe it and conceive of it, in some meaningful way defined by actual reality, a thing.

It could be that it's ten different things that aren't actually connected at all, but happen to look kinda similar. Some of which either are a variant of ADHD (or vice-versa, doesn't much matter) or just happen to include similar symptoms and behaviors that respond well to the same drugs and therapies we use to tread ADHD.

(now, to some degree we do have real tests we can do to pick up e.g. genetic markers of certain disorders, but these largely remain just another clue, not exactly solid proof, with some exceptions)

To illustrate: imagine we couldn't ever see the inside of a human body and just had to guess at what was going on when something went wrong. We'd probably have something we just called "bad kidney" that was actually several different problems, and we'd just throw drugs and other therapies at it until (often, but not always) some set of those relieved the symptoms. Meanwhile, sometimes it's a kidney stone, sometimes it's cancer, et c. And maybe we even have a whole step that's trying to figure out if it's "bad kidney" or "bad bladder" and sometimes we'd get that right, but sometimes wrong, but also some of the same medicines work for either (depending on the actual cause) so we might incorrectly diagnose "bad kidney" then accidentally correctly treat "bad bladder", and think we were right all along.

> how big could a potential overlap be between ADHD and autism?

The lack of executive function is overlapping, but this particular post might be more of an ADHD simulator.

The very first "Follow the morning routine" or not is where this veers off my experience of the spectrum.

"Changing plans because of situations internal or external" is hard.

The option should've been "Spend 20 minutes making eggs again, because the yolks weren't the right kind of runny", miss the train, take a cab to work, but tell the driver that you've now got a system for eggs which you didn't have today (yeah, fun fact, the recipe was off because they don't refrigerate them over in France).

There seems to be a prevalent pop psych view that a bunch of these conditions (Autism, ADHD, Anxiety-Depression, OCD) are sort of clustered together and people who manifest one will often manifest symptoms of others. It gets muddier because a lot of these conditions are understood as spectrums and different people who identify with them may manifest them in vastly different ways. I'm still hesitant that "autism" these days may describe either someone who's completely nonverbal and living in assisted living, or someone who's a successful academic/engineer/entrepreneur.

The diagnostic criteria and symptoms have substantial overlap, ultimately everything in the DSM is a descriptive diagnosis not based on a mechanistic understanding of neurobiology so it's VERY likely that our categories don't map 1:1 to the underlying causes.

One is impulsive, the other requires structure. The two are not mutually exclusive though, because both conditions are pretty diverse. AuDHD is a term used to describe people with both.

Not offensive at all, in fact there's a massive overlap. See the chart at https://neurodivergentinsights.com/adhd-vs-autism/

I've seen Twitter use "AuDHD" for the intersection. It's big enough to have its own label and subgroup who identify with it.

Not at all - the stat I've heard is that 30-50% of autistics also have ADHD

Significant enough that the DSM-iV recognized ADHD symptoms as symptoms of autism and didn't allow a comorbid diagnosis of both conditions because of this. (The DSM-V does recognize both as possibly occurring together.)

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