> It seems more like a horoscope to me - everyone can find themselves in the criteria. It’s an observable thing, I’m just not sure I buy its special distinction

Do you think the same about conditions like Autism or OCD?

People often say they "are a little bit" OCD or autistic, but it's the degree to which those traits are experienced which is the differentiation. There is also no objective test, it's all "soft" science.

> People also used to make the claim that the stimulant drugs had special effects (or even opposite effects) on those with ADHD vs. the non ADHD population

This is my experience, but I understand that anecdotes aren't good evidence.

FWIW I don’t think the same about autism and OCD (at least not to the same extent). There are some similar problems with the soft diagnosis, but there is more going on there imo.

They both do have problems with variableness (particularly autism), but it’s more distinct from the general public.

My "personal hypothesis" is that the ADHD/Autism/OCD are fundamentally related somehow. The comorbidity between them is much higher than general population incidence, there's large symptom overlap, on a personal level I've found that I relate to and get on along much better with people who have at least one of those conditions, and a good 2/3rds of the people I consider close friends do.

I largely agree with you but it's not quite as generic as horoscopes and similar can be. Let's look at the DSM-V's diagnostic criteria for ADHD:

A. A persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development, as characterized by (1) and/or (2). B. Several inattentive or hyperactive-impulsive symptoms were present prior to age 12 years. C. Several inattentive or hyperactive-impulsive symptoms are present in two or more settings (e.g. at home, school, or work; with friends or relatives; in other activities). D. There is clear evidence that the symptoms interfere with, or reduce the quality of, social, academic, or occupational functioning. E. The symptoms do not occur exclusively during the course of schizophrenia or another psychotic disorder and are not better explained by another mental disorder (e.g. mood disorder, anxiety disorder, dissociative disorder, personality disorder, substance intoxication or withdrawal).

I think E is probably a common miss, and fits with ADHD being over-diagnosed vs. other disorders that can have overlapping symptoms. The differential diagnosis section could perhaps be more detailed. But now briefly looking at A's (1) and (2). (1) Inattention: Six (or more) of the following symptoms have persisted for at least 6 months ... (lists 9 symptoms related to forms of inattention, the most generic of which I think is just f: "Often avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (e.g. schoolwork or homework; for older adolescents and adults, preparing reports, completing forms, reviewing lengthy papers)") (2) Hyperactivity and impulsivity: Six (or more) of the following symptoms .. (lists another 9 symptoms -- I count 3 pretty generic ones in a. (often fidgeting), f. (often talking excessively), and g. (often not waiting for a turn in conversation or completing people's sentences -- common in online meetings)).

While flawed I think this is enough detail to diagnose someone and clearly say "you're different", it's not nearly as broad as a horoscope "this sign is strong" or "that sign is deep" language and similar. The "Often" qualifier does a lot of work. Nevertheless, two people can both be diagnosed with "ADHD" and yet have few to no overlapping diagnostic symptoms.