Pervasive Developmental Disorders (PDDs)

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 a toddler, 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.

What Conditions Are Considered Pervasive Developmental Disorders?

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 three out of every four -- children with autism also have some degree of intellectual disability. Children with autism can frequently have seizures as well as low muscle tone. They also have underlying anxiety and resistance to change.
  • Asperger's syndrome : Like children with autism, children with Asperger's syndrome have difficulty with social interaction and communication. They also 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 have difficulty concentrating and may have poor coordination. Asperger's is usually not recognized until children have enough language skills to show a limited focus and unusual patterns of speech.
  • Childhood disintegrative disorder: Children with this rare condition begin their development normally in all areas, physical and mental. At some point, usually between ages 2 and 10, 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 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 (PDD-NOS): 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.


What Are the Symptoms of Pervasive Developmental Disorders?

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 that range 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.
  • Temper tantrums
  • Difficulty sleeping
  • Aggressive behavior
  • Fearfulness or anxiety

What Causes Pervasive Developmental Disorders?

The cause of pervasive developmental disorders is not known, but researchers are looking for answers. Many genes have been implicated as contributing to autism as have some biochemical or metabolic disorders. Some studies suggest that PDDs are caused by a problem with the nervous system (brain and spinal cord). Studies currently in progress are examining the structure and function of the brain in people with autism for clues that may help us better understand these conditions as well as how to treat and prevent them.

How Common Are Pervasive Developmental Disorders?

It is estimated that pervasive development disorders occur in about one in 88 children. In general, PDDs are more common in boys than in girls with the exception of Rett syndrome, which occurs almost always in girls.

How Are Pervasive Developmental Disorders Diagnosed?

If symptoms of a pervasive development disorder are present, the doctor will begin an evaluation by performing a complete medical history and physical exam along with a developmental screening questionnaire. Although there are no laboratory tests to diagnose a PDD, the doctor may use various imaging studies and blood tests to determine if there is a physical disorder causing the symptoms.


If no physical disorder is found, the child may be referred to a specialist in childhood development disorders, such as a child and adolescent psychiatrist or psychologist, pediatric neurologist, developmental-behavioral pediatrician, or other health professionals who are specially trained to diagnose and treat PDDs. The doctor bases his or her diagnosis on the child's level of development and the child's speech and behavior, including his or her play and ability to socialize with others. The doctor often seeks input from the child's parents, teachers, and other adults who are familiar with the child in different environments and recognize the child’s symptoms.

Developmental testing, mental and neurological examinations, as well as parent and teacher input, will all be used to make the diagnosis.

How Are Pervasive Developmental Disorders Treated?

Because children with pervasive developmental disorders have a range of symptoms and abilities, a plan of therapy must be developed with the child's specific needs in mind. The treatment plan -- or more appropriately, a program of intervention -- will address the child's needs at home and at school. For that reason, intervention planning is a cooperative effort of the parents, health care providers, teachers, and others who may be needed to provide services. This may include counselors, social workers, and occupational, physical, or speech therapists. The plan aims to promote better socializing and communication and reduce behaviors that can interfere with learning and functioning.

A plan of care for a child with a PDD may include:

  • Special education: Education is structured to meet the child's unique educational needs. The goal is always to provide the “least restrictive environment,” which refers to an education setting that is as similar as possible to that of peers without such needs.
  • Behavior modification: This may include strategies for supporting positive behavior by the child.
  • Speech, physical, or occupational therapy: These therapies are designed to increase the child's functional abilities.
  • Medication : There are no drugs to treat the PDDs themselves. Medications may be used, however, to treat specific symptoms such as anxiety, hyperactivity, and behavior that may result in injury. If a child has a seizure disorder in association with the PPD, then the child may be on or need antiepileptic medications.


What Research Is Being Done on Pervasive Developmental Disorders?

Most of the research being done on pervasive developmental disorders focuses on learning more about the causes of these disorders, specifically what is going on in the brain. The goal is to use this knowledge to develop better techniques for diagnosing and treating these disorders, ultimately leading to prevention and cure.

What Is the Outlook for People With Pervasive Developmental Disorders?

The outlook varies depending on the type and severity of the pervasive development disorder, the age at which treatment is started, and the availability of supportive resources for the child. Most children with PDDs will continue to have some problems with communication and socialization, but many can experience a significant increase in function with early intervention.

Can Pervasive Developmental Disorders Be Prevented?

Until more is known about the causes of pervasive development disorders, it is not possible to prevent them. However, the sooner a child with symptoms begins treatment, the better he or she will do in the long run.

If the child is not reaching his milestones or seems to be delayed, it is very important for parents to discuss any concerns they may have about their child with the child's pediatrician.

WebMD Medical Reference Reviewed by Amita Shroff, MD on May 22, 2015



National Institute of Neurological Disorders and Stroke. "Least Restrictive Environment, Mainstreaming, and Inclusion."



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