i asked my mother who works in pharmaceutics about ahdh and ritalin , and she explained me a bit on ahdh and how is ritalin is supposed to work with that =)

she told me ahdh is supposed to be caused by some neurons in charge of filtering what come from our sense that would not work correctly like under filtering our senses and provoke an overwhelming of stimulus which cause nervousity and hyperactivity and difficulty to focus etc , and so ritalin is supposed to stimulate brain activity leading to a more efficient work of these filter neurons