I think how it technically works are there are three components to ADHD, two of which are linked. There are 3 diagnostic "types"

1. Hyperactivity, which changes in adults more into restlessness/driving fast etc.
2. Impulsivity, which is linked with 1
3. Inattentiveness. Poor working memory, crappy executive function, no sense of time, etc.

The major type, and its mostly boys is ADHD Combined. Which is both (1&2) + (3)
The next type, mostly girls, is ADHD Primary Inattentive. Which is mostly (3) but can have some components of (1&2)
The last, rarer type, is ADHD/Hyperactive, which is mostly (1&2) but again, can have some components of (3)

Each component (Hyperactivity, Impulsiveness, Inattention) are all, like so many psychological or neurological conditions, on a spectrum.

I can assure you that boys can definitely be ADHD/PI too, and like girls, they'd be more likely to be diagnosed late, too. The reverse is also true. Stereotypes hurt everyone.

The T that I saw speak at CHAAD (when I felt so awful and alone that I was the ONLY AD/HD person in a room of 30 without any medication,) said that she was diagnosed at 50!

Thanks Wikid. Its a pleasure to be amongst a wonderful group.