The term “pervasive development disorders,” also called PDDs, refers to a group of conditions that involve delays in the development of many basic skills, most notably 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 3 years of age — a critical period in a child’s development — they are called development disorders. Although the condition begins far earlier than 3 years of age, parents often do not notice a problem until the child is a toddler who is not walking, talking, or developing as well as other children of the same age.
There are five types of pervasive development disorders:
- Autism: Children with autism have problems with social interaction, pretend play, and communication. They also have a limited range of activities and interests. Many (nearly 75%) of children with autism also have some degree of mental retardation.
- Asperger’s syndrome: Like children with autism, children with Asperger’s syndrome have difficulty with social interaction and communication, and have a narrow range of interests. However, children with Asperger’s have average or above average intelligence, and develop normally in the areas of language and cognition (the mental processes related to thinking and learning). Children with Asperger’s often also have difficulty concentrating and may have poor coordination.
- Childhood disintegrative disorder: Children with this rare condition begin their development normally in all areas, physical and mental. At some point, usually between 2 and 10 years of age, a child with this illness loses many of the skills he or she has developed. In addition to the loss of social and language skills, a child with disintegrative disorder may lose control of other functions, including bowel and bladder control.
- Rett’s syndrome: Children with this very rare disorder have the symptoms associated with a PDD and also suffer problems with physical development. They generally suffer the loss of many motor or movement, skills — such as walking and use of their hands — and develop poor coordination. This condition has been linked to a defect on the X chromosome, so it almost always affects girls.
- Pervasive development disorder not otherwise specified (PDDNOS): 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.
The use of the word “pervasive” to describe these illnesses is somewhat misleading. The definition of pervasive is “to be present throughout,” but children with PDDs generally do not have problems in all areas of functioning. Rather, most children with PDDs have specific problem areas and often function very well in other areas.
Children with PDDs, such as autism, can display a wide range of symptoms which can range in severity from mild to disabling. They also vary widely in their individual abilities, intelligence, and behavior.
General symptoms that may be present to some degree in a child with a PDD include:
- Difficulty with verbal communication, including problems using and understanding language.
- Difficulty with non-verbal communication, such as gestures and facial expressions.
- Difficulty with social interaction, including relating to people and to his or her surroundings.
- Unusual ways of playing with toys and other objects.
- Difficulty adjusting to changes in routine or familiar surroundings.
- Repetitive body movements or patterns of behavior, such as hand flapping, spinning and, head banging.
- Changing response to sound. (The child may be very sensitive to some noises and seem to not hear others.)