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4. A short review of the different PDD's

There are five types of PDD's.

  1. Childhood autism
  2. Asperger's syndrome
  3. Childhood disintegrative disorder
  4. Rett's disease
  5. PDD NOS or pervasive developmental disorder not otherwise specified

This section will give general guidelines, providing a superficial understanding of the differences between these above-mentioned disorders. A better, more specific understanding of these disorders is given by the specific DSM IV criteria for each disorder.

A. Childhood autism

Always presents before 36 months of age, these children may have some speech developmental and social interactive regression, usually around 18 months of age. The diagnosis of childhood autism must meet the specific DSM IV criteria and will therefore present with poor eye contact, pervasive ignoring, language delay, and other features. Per definition, these children will have a severe impairment in speech, communication, or social interaction. Many of them will be completely non-verbal and "in their own world."

B. Asperger's syndrome

These are kids with a form of autism that affects language less, yet there are difficulties with appropriate speech and communicative development. Mostly, however, these children have social interaction difficulties and impairments related to a restricted, repetitive, stereotype behavior. These kids may have very high IQ's, may do very well academically, have a superior memory for "unimportant" details, such as the birth dates of all baseball players, some historical or geographical trivia, yet they lack the skills to care for themselves and live independently. These individuals may talk repetitively about a certain topic without understanding that it may be boring to others. The "amount" of memory of these individuals is incredible and one may expect different degrees of impairments with Asperger's syndrome. This may involve more or less memory and more or less social communicative impairment with regards to being able to live independently. As long as a child or individual seems "different" or "odd" and has a thought process that doesn't fit the way everyone else thinks, yet shows some of the required autistic characteristics, Asperger's syndrome should be considered. Many people with this condition remain undiagnosed because of their ability to compensate with their memory or excellent academic abilities, yet they are considered by others to be "socially inept," "weird," "nerds," "bizarre," "eccentric," etc.

A typical example of a child with Asperger's syndrome would be that of a child who has some odd behaviors, poor eye contact, "sluggish" social interaction abilities, and an extreme interest in a central topic such as a washing machine. The child likes to sit and watch the washing machine door rotate, knows everything about it including its operative and professional manual and may spend hours perseverating about it. Such a child when he has a play date, may try to involve his "friend" in his most exciting interest (the washing machine) without realizing how boring it is to others and that will be the end of the play dates forever. This pattern may present itself in different degrees and circumstances, but the prinicipal is the same: the lack of the ability to understand how other people perceive what you do, say, or express with body language and facial expressions.

C. Childhood disintegrative disorder

These are kids who develop normally for the first 3 years of life. Later they seem to regress and develop some autistic features associated with a severe functional impairment. These children must be thoroughly evaluated for the possibility of the development of seizures, affecting the speech areas of the brain, or Landau Kleffner syndrome (acquired epileptiform aphrasia), where seizure activity "robs" the brain from previously acquired speech.

D. Rett's disease

This affects only girls. These are girls who develop normally until 6 months of age and regress. Their regression is associated with microcephaly (small head). The head size seems to stop growing from 6 months and on, from the time of the observed regression. Recently a specific chromosomal marker (MEC-P-2) has been associated with this disorder and is now commercially available in some laboratories.


PDD NOS will present similarly to the kids who have autism (some people argue that these conditions should be combined as one), but will have a lesser degree of a severe impairment. These kids are more likely to be verbal and have some degree of verbal or non-verbal effective communication, yet they must have the autistic features (as per the DSM IV criteria) and a severe impairment in social interaction, communication, or repetitive stereotype behavior. This term is reserved for children with a severe impairment who do not fully qualify for any other autistic diagnosis, due to age of onset or combination of autistic features.

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Other topics in the PDD/Autism section:
PDD Main Page
1. What is PDD or autism? | 2. How is PDD or autism diagnosed?
3. The DSMV IV criteria
4. Review of the different PDDs
5. How does a typical child with autism present?
6. The PDD assessment questionnaire
7. Who should be evaluated for PDD?
8. What are the causes? | 9. Lab testing, medical consensus guidelines
10. What is the best treatment?
11. Behavioral modification
12. Prognosis (long term outcome) of autism
13. Differential diagnosis for autism
14. Secretin and autism
15. PDD and the educational system
16. Associations related to PDD (Links)
[Print entire PDD section]

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