This is a not-very-edited post on response rate for medication based on subtype of ADHD, which I'll update as I learn more:
Stimulants (especially methyphenidate):
There's some data that methylphenidate is more effective for ADHD-C than it is for ADHD-PI. For example:
There's a clear linear dose-response relationship for methylphenidate for kids with ADHD-C (where higher dose leads to better response). However, children with ADHD-PI have a better response at *lower* doses than they do at higher doses.
Studies suggest kids with ADHD-PI don't get as much benefit from the med at *any* dose as kids with ADHD-C , although other studies have not found any difference.
More recent research suggests that the slow/sluggish cognitive tempo might be the factor that best predicts non-response to methylphenidate in some kids with ADHD-PI.
Non-Stimulants (e.g., atomoxetine; guanfacine):
Clinically, I hear from psychiatrists that kids with ADHD-PI may respond better to a non-stimulant medication, but as far as I can tell, actual research supporting that is sparse (happy to be pointed to any research that shows otherwise!). However, we do know that:
The general response rate to methylphenidate is higher than the response rate to atomoxetine (56% to 45%). We also know many kids who do not respond to one class of med do respond to the other, suggesting preferential response.
However, that preferential response is probably not by subtype in my reading. The research I've seen on guanfacine looks equivocal so far, with kids with ADHD-C seeming to show a better level of response to the medication, but probably because they were rated as having more problems to begin with.
Same results as above with guanfacine + stimulant polytherapy.
New Medications (e.g., Metadoxine):
I've seen some research in adults suggesting metadoxine will be more effective for ADHD-PI than it is for ADHD-C , but they are also looking at metadoxine for kids with Fragile X (who generally look more like kids with the combined type) so maybe the medication will have a different response for kids.
Hyperactive-Impulsive Subtype of ADHD:
I'm not familiar with any research on the ADHD-HI subtype and medication response. Most of the research I've seen included a line that says something like "we couldn't find enough ADHD-HI kids to look at them as a separate group" (which is in line with research suggesting ADHD-HI may just be kids who are not yet old enough to get a diagnosis of ADHD-C).