The term “pervasive developmental disorders,” also called PDDs, refers to a group of conditions that involve delays in the development of many basic skills. Most notable among them are the ability to socialize with others, to communicate, and to use imagination. Children with these conditions often are confused in their thinking and generally have problems understanding the world around them.
Because these conditions typically are identified in children around age 3 — a critical period in a child’s development — they are called developmental disorders. The condition actually starts far earlier than age 3, but parents often do not notice a problem until the child is atoddler, when differences in children of the same age can be more obvious or noted. These children may still not be walking, talking, or developing in the same way as their peers.
This category is used to refer to children who have significant problems with communication and play, and some difficulty interacting with others, but are too social to be considered autistic. It’s sometimes referred to as a milder form of autism.