Inattentiveness:

"To help us with differential diagnosis, to help us tell ADHD form an anxiety disorder and from autism and all the other psychiatric disorders, which all interfere with attention at some point in life, ADHD is not the only attention deficit, we need to be more precise. If someone comes to us and says: 'My child or I am inattentive.' That is useless diagnostically. What I need to know is the nature of the inattentiveness. And we have now known for a decade that the inattentiveness that we see in ADHD is distinct from that produced by all other disorders. Because it is most, I think, accurately described as a failure of persistence. The first attention problem is persistence toward a goal. ... ADHD is not a problem of perception, of filtering, of processing, of how the posterior part of our brain functions. "

Russell Barkley