A specific cause of ADHD is not known. There are, however, a number of factors that may contribute to ADHD including genetics, diet and social and physical environments.
Attention-deficit/hyperactivity disorder (ADHD or AD/HD) is a neurobehavioral developmental disorder. ADHD is primarily characterized by "the co-existence of attentional problems and hyperactivity, with each behavior happening rarely alone." While symptoms may appear to be innocent and merely annoying nuisances to observers, "if left untreated, the persistent and pervasive effects of ADHD symptoms can insidiously and severely interfere with one's ability to get the most out of education, fulfill one's potential in the workplace, establish and maintain interpersonal relationships, and maintain a generally positive sense of self."