Been seeing a lot of autistic-ADHD discourse on my timeline, so some thoughts?

So basically I think that autism and ADHD are distinct conditions with a high cooccurrence rate (currently seems to be assumed to be about 30%) and I think it's useful to describe them as separate

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So I get that some people find it to be an appealing idea that ADHD is a subset of autism or that Autism-ADHD are part of the same spectrum but I don't think that's true although cooccurrence and overlap are the norm rather than the exception

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Firstly, I personally experience ADHD and autism as quite distinctive forces within me, although there are some grey areas and the underlying cognitive mechanisms feel quite different?

Autism feels like monotropic focus and repetition. ADHD feels like seeking stimulation.

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Those two things, of course, have a lot in common and can overlap when you only have one or the other, and can amplify each other when you have both: hence I think that hyperfocus/hyperfixation and stimming are shared characteristics (although they work a bit differently).

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But I've always understood them as creating a lot of internal tension as separate kind of drives or cognitive processes, especially starting with @mykola's thread

https://twitter.com/mykola/status/1221847321606074368

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There's also the fact that research has found that some traits are distinct:

"Effect sizes showed clear deficits of ADHD children in inhibition and working memory tasks. Participants with ASD were impaired in planning and flexibility abilities."

https://twitter.com/barisanhantu/status/1256420953476612096

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So working memory issues are distinctly an ADHD problem. Moreover when comorbid, those diagnosed autism+ADHD seemed to have less problems with working memory but executive dysfunction affects both ADHD and autism. I'd describe myself as predominantly ADHD in this sense.

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The 30% figure may come from the fact that 31.6% of autistic children/teens are on ADHD medication. I personally suspect it is underdiagnosed, but it gives us a rough sense of who many people have both. Anecdotally, ADHD meds don't work as well for those of us with both.

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So the idea that all ADHD and autism is the same likely comes from the fact that the subgroup discussing this is mostly late-diagnosed so this may be a selection bias - i.e. if you have both you're more likely to be late-diagnosed because you presented differently

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Not to say all late-diagnosed ADHD and/or autistic people have both; but it's likely a large percentage of us are late-diagnosed because having both means you have atypical traits of ADHD and atypical traits of autism because the two interact/fuse/cancel each other

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I don't research has fully looked into this because the understanding of ADHD and autism are largely behavioural so there doesn't seem to me to be an awareness of how the two interact internally.

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And guess what: both ADHD and autism are defined as "naughty boy" or "male brain" syndromes so if you are AFAB and/or a marginalised gender you're more likely to get missed for both or get diagnosed with one and miss the other.

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The fact that ADHD women are 2.5 times more likely to have autistic children indicates to me that a lot of ADHD women are undiagnosed autistic women (and 6 times more likely to have ADHD children)

https://twitter.com/neuroqueery/status/1311685681673121793?s=20

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Assuming genetic likelihood of passing down ADHD and autism are the same, it looks like 40% of the ADHD women in that study might be autistic (2.5/6) this is honestly a stab in a dark from me (idk if the numbers do work that way), but 40% seems like a reasonable amount.

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There are many ways to think about the ADHD-autism overlap, but if you think about how ADHD and autism diagnoses select individuals out of the population, it's likely we won't be able to make sense of this until we look at the broader phenotype?

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You basically get the diagnosis if you stand out during childhood or if you start to struggle a lot later in life, which means that we're really only selecting for people who don't fit in. There may be plenty of ADHD and/or autistic people who don't struggle visibly

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So one possibility is that coocurrence rates are high in any kind of neurodivergence not because coocurrence is genetically linked but because coocurrence is selected for (i.e. you struggle because you have more than one thing going on).

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(Sidenote: The other possibility I've speculated on is that as neurodivergent folk, erm ADHD people and autistic people might be more drawn to each other and yknow pass down both their traits to their children.)

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But at the end of the day, I find it useful to unpick cooccurring conditions if they have some kind of new explanatory power and I feel like the problem of autism from the get-go is conflating multiple co-occuring conditions under autism

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Kanner and Asperger both selected groups of children who were outliers in terms of their behaviour and cognition, then slapped a label on them. It may be the case, imo, that autism is really broad spectrum because it looks so different when you add in multiple conditions.

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There are so many levels of selection bias going on here that it's difficult to talk about the categories meaningfully. Internal experiences and how they conflict are probably useful to begin unpicking the things that are conflated. This is all very speculative on my part.

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But beyond the scientific conception of autism/adhd, cooccurence and overlap, I do think we should talk about the categories from other perspectives, as socially constructed, as identity, as cognition etc. and even there it's probably useful to distinguish between the two.

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