Developmental psychopathology is the study of how disorders arise and change with time. In general, childhood is associated with significant developmental changes that follow a specific pattern. As a result, any disruption in the development of early skills will likely disrupt the development of later skills. The disorders covered in this chapter are usually diagnosed first in infancy, childhood, or adolescence and include attention deficit/hyperactivity disorder (adhd), learning disorders, autism, and lastly mental retardation. The primary characteristics of persons with attention deficit/hyperactivity disorder (adhd) are inattention, overactivity, and impulsivity. Such persons start many tasks but rarely finish them, have trouble concentrating, and do not seem to pay attention when others speak. Children with adhd are often described as fidgety in school, and often are unable to sit still for more than a few minutes. The textbook illustrates adhd with the case of danny. The dsm-iv-tr differentiates two clusters of adhd symptoms. The second cluster includes symptoms of hyperactivity and impulsivity.