Whether "attention deficit" is a disorder or not depends upon just what it is you are supposed to be paying attention to. Teachers who are b-o-r-i-n-g? Political speeches? Too-long movies or performances or lectures?
It shouldn't routinely be called a "disorder." It could be due to high spirits, an inquiring mind, an interest in the world in general. I wish parents would resist concluding there's something automatically wrong with lack of attention, and chemical"solutions" to same.