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Asia’s First Neurofeedback Centre (Established 1995)


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What is Pervasive Developmental Disorder (PDD)?

Pervasive Developmental Disorders (PDD) is actually a name given to a group of five specific disorders that includes:

Pervasive Developmental Disorder (PDD)

Autistic Spectrum Disorder (ASD)

  1. Autism
  2. Asperger Syndrome (AS)
  3. Pervasive Developmental Disorder not otherwise specified (PDD-NOS)

  1. Childhood Disintegrative Disorder (CDD)
  2. Rett Syndrome (RS)

The first three of these disorders are commonly called the Autism Spectrum Disorders (ASD); the last two disorders are much rarer, and are sometimes placed in the autism spectrum and sometimes not.

These five disorders are characterized by delays in the development of multiple basic functions including socialization and communication. Parents may note symptoms of one of the PDD disorders as early as infancy and typically onset is prior to three years of age.

Typical Symptoms of Autistic Spectrum Disorder (ASD)


Autism is characterized by delays or abnormal functioning before the age of three years in one or more of the following domains:

  1. social interaction;
  1. communication; and
  2. restricted, repetitive, and stereotyped patterns of behavior, interests, and activities

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Asperger syndrome (AS):

Asperger syndrome can be distinguished from autism

  1. by the lack of delay or deviance in early language development
  1. peculiarities in speech and language
  2. no significant cognitive delays
  3. repetitive routines or rituals
  4. inappropriate affect or social behavior
  5. problems with non-verbal communication
  6. clumsy or uncoordinated motor movements

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Pervasive Developmental Disorder not otherwise specified (PDD-NOS):

PDD-NOS is considered "subthreshold autism" and "atypical autism" because it is often characterized by milder symptoms of autism or symptoms in only one domain (such as social difficulties).Persons with PDD-NOS may demonstrate pervasive deficits in the development of reciprocal social interaction or stereotyped behaviors, but do not meet the criteria for a specific pervasive developmental disorder or other psychological disorders (such as schizophrenia or avoidant personality disorder).

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Pervasive Developmental Disorder (PDD)

Confusing terms:

PDD or “pervasive developmental disorders” refers to a group of five disorders .

“pervasive developmental disorders not otherwise specified” (PDD-NOS) refers to a specific disorder.

Finding the Causes

Most clinicians do not bother about the causes as diagnosis is based on behavioral symptoms …   

At Spectrum Learning, we have been investigating the possible causes …

Pervasive Developmental Disorder (PDD)