PDDs is the acronym of Pervasive Developmental Disorders which is a category of Disorders characterized by severe and extensive impairments in social interaction and communication skills, along with stereotyped patterns of behaviors, interests, and activities. These are conditions that begin in childhood and have a major impact on social and cognitive functioning; involve serious deficits in social interaction and communication skills, as well as odd behavior, interests, and activities.
Lexicon of Psychology - Terms, Treatments, Biographies,