One reason I believe it is important to redefine ADHD is that what it really describes is executive function – attention and impulse control are processes in the Executive system – the control of input on the one hand and output on the other. And, as I’ve discussed elsewhere (ThinkPrint), the Executive system depends on input from the Affective system, and is very sensitive to problems from fatigue, illness, and emotional upset.
So we can define Executive Dysfuntion as a disorder, and include folks who, for example, have anxiety – which interferes with attention and impulse control – and not make the mistake of equating the symptom as the disease.