The symptoms tend to appear together, just like many datasets it is not some perfect line or cluster of symptoms that always appear together at the same time for everyone. Sure, maybe some statistical analysis will reveal that some symptoms should belong in the classification of adhd and others shouldn’t, but given the near infinite possible symptoms a person may exhibit, it’s interesting that there are a few that seem to appear often.

It’s not just ADHD. Consider OCD, while there are several sub types and triggers, many of the traits and rituals are very similar (repetitive washing, locking of doors, uncomfortably violent ideation) so much so that it’s clear they are related.

And if you’re a familiar of these people, you will experience their condition undoubtedly, when compared to a neurotypical.