developmental disorder, pervasive

developmental disorder, pervasive A class of disorders in which the patient shows impairment in social interaction, imaginative activity, and verbal and nonverbal communication skills, and has a limited number of interests and activities that tend to be repetitive (stereotyped). Abbreviated PDD. All types of PDDs are disorders of the nervous system that are usually evident by age 3. In general, children who have PDDs have difficulty talking, playing with other children, and relating to others, including their family members. The types of PDD include autistic disorder, Rett syndrome, childhood disintegrative disorder, Asperger syndrome, and “pervasive developmental disorder not otherwise specified.” See also Asperger syndrome; autism; childhood disintegrative disorder; Rett syndrome.