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Autism Spectrum Disorders Health Center

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Pervasive Developmental Disorders (PDDs)

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.

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