Wasn’t there already research suggesting there is ADHD but without AD, ADHD but without H and also ADHD with both attention deficiancy and hyperactivity? Is this the same theory?

Edit: better to read first and comment after, this is from the article:

In the new study, the first two categories map neatly onto the way ADHD is currently diagnosed, dividing along a well-established line between difficulties with focus and problems with hyperactivity and impulse control.

The third, however, pushes the field into new territory.

This extreme subtype exhibited the most extensive changes across the brain – a total of 45 abnormal areas versus 26 each for the other two subgroups.