Yes, they do, because the baseline availability of dopamine and noradrenaline (it affects both of them) as well as 5-HT is considerably lower in someone with AD

Yes, they do, because the baseline availability of dopamine and noradrenaline (it affects both of them) as well as 5-HT is considerably lower in someone with ADHD than without, though 5-HT doesn't have much of a role to play in attention disorders. It also has a sympathetic serotonergic effect (edit: that is to say, that the increase in 5-HT is similar to taking an SSRI. 5-HT is serotonin.) The fact is, there are proven anatomical changes that are strongly correlated with attention disorders, and the efficacy of the dopamine/noradrenaline systems in the brain is significantly impaired by someone with such a condition. And, as someone with such a condition, I can attest to my baseline being very different from someone without an attention disorder. Further, the effect that I experience from taking Adderall is one of calmness and focus, while friends who have taken diverted pills say they feel "edgy" and focused, because its effect on me is to increase a low-baseline of the relevant neurotransmitters, and someone without a related attention disorder would have their baseline availability increased far above the therapeutic levels I experience. Self-reports from recreational users on web sites devoted to nootropics or to recreational drug use seem to agree with that assessment with considerable frequency. Maybe that helps explain why people persist in saying that someone with ADHD has a different experience with stimulants? Edit: I'll also add that my level of focus on stimulants still requires me to be somewhat interested in what I'm doing, and that doesn't seem to be the case with non-affected users, who seem to hyperfocus on whatever catches their attention first. Almost as if taking the drug gives them an attention disorder because they have too much dopamine and noradrenaline.