By Luke Y. Tsai, M.D.
(excerpt)
According to the NICHCY, the term Pervasive Developmental Disorders was first used in the 1980's to describe a class of disorders which have the following characteristics in common:
- Impairments in social interaction
- Imaginative activity,
- verbal and nonverbal communication skills, and a
- limited number of interests and activities that tend to be repetitive.
The DSM was last revised in 1994 and is known today as the Diagnostic and Statistical Manual, Fourth Edition, Text Revision (DSM-IV-TR).
Five Disorders are identified under the category of Pervasive Developmental Disorders:
- Autistic Disorder
- Rett's Disorder
- Childhood Disintegrative Disorder
- Asperger's Disorder, and
- Pervasive Developmental Disorder Not Otherwise Specified, or PDDNOS
Many of the questions parents and education professionals ask NICHCY have to do with children who have been diagnosed with "PDD." Doctors are divided on the use of the term PDD. Many professionals use the term PDD as a short way of saying PDDNOS. Some doctors, however, are hesitant to diagnose very young children with a specific type of PDD, such as Autistic Disorder, and therefore only use the general category label of PDD. This approach contributes to the confusion about the term, because the term PDD actually refers to a category of disorders and is not a diagnostic label.
The appropriate diagnostic label to be used is PDDNOS-Pervasive Developmental disorder Not Otherwise Specified-not PDD (the umbrella category under which PDDNOS is found)
All of the disorders that fall under the category of PDD share, to some extent, similar characteristics. To understand how the disorders differ and how they are alike, it's useful to look at the definition of each.
Definition of the PDD Category and its Five Specific Disorders. All types of PDD are neurological disorders that are usually evident by age three. In general, children who have a type of PDD have difficulty in talking, playing with other children and relating to others, including their family.
According to the definition set forth in the DSM-IV (American Psychiatric Association, 1994), Pervasive Developmental Disorders are characterized by sever and pervasive impairment in several areas of development:
Social interaction skills; Communication skills; or The presence of stereotyped behavior, interests, and activities
The Five Types of PDD
- Autistic Disorder. Autistic Disorder, sometimes referred to as early infantile autism or childhood autism, is four times more common in boys than in girls. Children with Autistic Disorder have a moderate to server range of communications, socialization, and behavior problems. Many children with autism also have mental retardation. The DSM-IV criteria by which Autistic Disorder is diagnosed are presented on page 3 of this Briefing Paper.
- Rett's Disorder. Rett's Disorder, also know as Rett Syndrome, is diagnosed primarily in females. In children with Rett's Disorder, development proceeds on an apparently normal fashion over an the first 6 to 18 months at which point parents notice a change in their child's behavior and some regression or loss of abilities, especially in gross motor skills such as walking and moving. This is followed by an obvious loss in abilities such as speech, reasoning, and hand use. The repition of certain meaningless gestures or movements is an important clue to diagnosing Rett's Disorder; these gestures typically consist of constant hand-wringing or hand-washing. (Moeschler, Gibbs, & Graham1990) The diagnostic criteria for Rett's Disorder as set forth in the DSM-IV appear on page 3 of this Briefing Paper.
- Childhood Disintegrative Disorder. Childhood Disintegrative Disorder, an extremely rare disorder, is a clearly apparent regression in multiple areas of functioning (such as the ability to move, bladder and bowel control, and social and language skills) following a period of at least 2 years of apparently normal development. By definition, childhood Disintegrative Disorder can only be diagnosed if the symptoms are preceded by at least 2 years of normal development and the onset of decline is prior to age 10. The Diagnostic Criteria for Childhood Disintegrative Disorder as set forth in the DSM-IV appear on page 4 of this Briefing Paper.
- Asperger's Disorder. Asperger's Disorder, also referred to as Asperger's or Asperger's Syndrome, is a developmental disorder characterized by a lack of social skills; difficulty with social relationships; poor coordination and poor concentration; and a restricted range of interest, but normal intelligence and adequate language skills in the areas of vocabulary and grammar. Asperger's Disorder appears to have a somewhat later onset than Autistic Disorder, or at least is recognized later. An individual with Asperger's Disorder does not possess a significant delay in language development; however, he or she may have difficulty understanding the subtleties used in conversation, such as irony and humor. Also, while many individuals with autism have mental retardation, a person with Asperger's possesses an average to above average intelligence (Autism Society of America, 1995). Asperger's is sometimes incorrectly referred to as "high-functioning autism." The Diagnostic Criteria for Aspergre's Disorder as set forth in the DSM-IV are presented on page 6 of this Briefing Paper.
- Pervasive Developmental Disorder Not Otherwise Specified. Children with PDDNOS either (a) do not fully meet the criteria of symptoms clinicians use to diagnose any of the four specific types of PDD above, and/or (b) do not have the degree of impairment described in any of the above four PDD specific types. According to the DSM-IV, this category should be used "when there is a severe and pervasive impairment in the development of social interaction or verbal and nonverbal communication skills, or when stereotyped behavior, interests, and activities are present, but the criteria are not met for a specific Pervasive Developmental Disorder, Schizophrenia, Schizotypal Personality Disorder, or Avoidant Personality Disorder" (American Psychiatric Association, 1194, pp. 77-78).
For more information on causes, treatments, therapies and education, or to receive a NICHCY Publications Catalog, contact NICHCY, P.O. Box 1492, Washington, DC. 20013. Telephone: 1-800-695-0285 (Voice/TTY) and (202) 884-8200 (Voice/TTY). Visit the Web site (http://www.nichcy.org) or the gopher site (gopheraed.org). Email: nichcy@aed.org