No, I don`t believe they are, at least not on the way these diseases are promoted and treated (with medications, while not searching for the real cause).
Of course I do believe that there are many people already born with "weak" or damaged nerves (due to the medications mothers use during the pregnancy, wrong diet, a lot of stress etc).
Ability to be calm and properly focused has nothing to do with any disorder - in human nature is to get focused only on the objects of the high interest - some people are able to move focus constantly because so many things are new and interesting- in the age when we are exposed to too many information, various media contents they automatically change in the front of us (TV, Internet... movies, news, games... exposure to constant marketing offers), various types of communication, noise and speed of modern life - isn`t it natural that young people develop lack of proper focus because they get exposed to this over-dynamic and chaotic way of life from the earliest age?
Brain overactivity often leads to physical overactivity, but brain overactivity is caused by constant change of various interesting (colourful and noisy) content which also, very often teaches people how to - misbehave, be hisyterical, do not listen authorities, that there is no need for patience, that everything can be achieved instantly and immediately etc.etc.
Mentioned epidemy of those disorders is direct product of "development" of human society.