Real. And a major genetic variant for it (DRD4-7r) is more common in Europeans than Africans, and WAY more common in both than in Asians.
You know what that variant is ALSO associated with? Global travel. People with it are more likely to want to explore the globe. You know where it's most commonly found? In the Americas.
>look up Prof. Russell Barkley
Seconding this.
Not necessarily. ADHD can be comorbid with depression, or be misdiagnosed AS depression.
Not necessarily to that "history of failure" part (though it depends on how you define "failure"). Really high-IQ people with it might not be "failures," just under-performers. High IQ can mask/compensate for a lot. Early childhood symptoms might be more subtle too.
Fuck no, I was on that shit until 16ish and all it did was drive me paranoid.