It is now known that ADHD does not dissipate with age. Some patients, however, might be able to compensate for some of their symptoms. At the same time, adults who were never diagnosed as children might start to exhibit ADHD symptoms as their compensatory mechanisms break down and they are faced with additional responsibilities, at work as well as in their social and home life.

It is necessary to recognize that the symptoms of ADHD evolve with age, and this chapter will explain how different behaviors are observed in each patient population. We know the disorder presents itself differently in children versus adolescents versus adults, and by understanding what the symptoms are at different stages, it will be easier to ascertain proper diagnosis and understand the treatment approaches presented in the following chapters.