"Hi, I have been reading your programmes. Can you tell me the difference between PDD and DD? Thank you." Pat

Answer: Susan Osborne, PhD, Coordinator, Graduate Program in Special Education, North Carolina State University

DD or Developmental Disorders are considered to be those that are usually diagnosed during infancy, childhood, or adolescence. These typically include mental disabilities (until recently called mental retardation), learning disabilities, attention-deficit and hyperactive behavior disorders, and communication disorders. One other category within Developmental Disorders is Pervasive Developmental Disorders or PDD. Pervasive Developmental Disorders involve severe and pervasive delay in several areas such as reciprocal social interactions, communication skills, and includes stereotypic behavior. Autism, Aspergers Syndrome, and Rhett's Disorder are included in the category Pervasive Developmental Disorders. The terms "Developmental Disorders" and "Pervasive Developmental Disorders" are more commonly used in the medical and psychiatric communities than in the educational community. Young children are often given the diagnosis DD or PDD before a more specific diagnosis can be made. Educators use terms like learning disabilities, mental disabilities, and behavioral/emotional disorders, and autism because diagnosis in these specific categories (among others) allows schools to work with parents to provide special education services.