alt Hacker NewsIf this PDF isn't triggering your skepticism, you need to adjust your sensitivity for pseudoscience. It's a PDF put together by an organization that sells "neurodiversity trainings for organizations". They try to lend legitimacy by linking to papers describing conditions, but their claim that these are all a "cluster" just goes to a YouTube video of their own webinar where they discuss their "lived experiences" as the basis for their claims.
The document mixes science with pseudoscience. It was put together by someone who subscribes to the current social media trends that blend together real diagnoses in a way that have been distorted and stretched to become generic catch-all explanations for vague conditions
This mess where conditions like MCAS, hEDS, POTS, and ADHD are all swirled together into a cluster of co-diagnoses is becoming a huge problem on social media. Even the individual groups for these conditions are become sick of the trend of pushing them all as co-diagnosis. One example from the ME/CFS forums sampling the frustration with how people incorrectly self-diagnosing with all of these conditions as a cluster is becoming a problem for each individual condition: https://www.s4me.info/threads/problems-arising-for-pwme-from...
This should be flagged away as it's both misinformation and a document serving as a lead gen for their training services based on misinformation (see the link at the bottom of the document)
The whole "clustering" thing is nonsense, but there is a real thing, known as "multimorbidity". There are conditions that are often found together, such that if you diagnose one, it's worth checking for the others. This isn't because the conditions are the same, but because some causal phenomenon (usually developmental) creates the circumstances for more than one condition. Premature birth appears somewhere in the causal network in a lot of cases, as does poverty. (I'm pretty sure poverty's a cause, though premature birth might be a result of the circumstances, rather than a cause.)
On that note, Wikipedia has a much better list than this PDF: https://en.wikipedia.org/wiki/Conditions_comorbid_to_autism. (This list is not without its flaws, but I at least find it easier to compensate for academic ignorance than magical thinking.)
Also related is differential diagnosis, which is a process by which clinicians distinguish between different diagnoses that have overlapping symptoms. (It's not a particular fancy technique, it's literally just the name for any approach that does that.)