Pervasive Developmental Disorders (PDD)/ Autism Spectrum Disorder (ASD)

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PDDs are characterized by widespread abnormalities of social interactions and communication, and severely restricted interests and highly repetitive behaviour. These symptoms do not imply sickness, fragility, or emotional disturbance.

The term autism spectrum or Autism Spectrum Disorder describes a range of conditions classified as neurodevelopmental disorders



Autism is a neurodevelopmental disorder characterized by impaired social interaction, verbal and non-verbal communication, and restricted and repetitive behaviour.

Signs and Symptoms

  1. Impairments in social interaction
  2. Impairments in communication
  3. Restricted interests
  4. Repetitive behaviour
  5. Atypical eating


A pediatrician commonly performs a preliminary investigation by taking developmental history and physically examining the child. If warranted, diagnosis and evaluations are conducted with help from ASD specialists, observing and assessing cognitive, communication, family and taking into account any associated medical conditions.

A differential diagnosis for ASD might also consider intellectual disability, hearing impairment, and specific language impairment.

ASD can sometimes be diagnosed by age 14 months, although diagnosis becomes increasingly stable over the first three years of life.


  1. High-functioning autism(HFA) is a term applied to people with autism who are deemed to be cognitively “higher functioning” (with an IQ of 70 or greater) than other people with autism.
  2. Regressive autism occurs when a child appears to develop typically but then starts to lose speech and social skills, typically between the ages of 15 and 30 months, and is subsequently diagnosed with autism.
  3. Syndromal autism is associated with severe or profound intellectual disability or a congenital syndrome with physical symptoms, such as tuberous sclerosis.


Pervasive Developmental Disorder (not otherwise specified)



PDD-NOS is a severe and pervasive impairment in the development of reciprocal social interaction or verbal and nonverbal communication skills. 

PDD-NOS is often called atypical autism, because some of the criteria for autistic disorder are not met.

Signs and symptoms

  1. Communication difficulties (e.g., using and understanding language)
  2. Difficulty with social behaviour
  3. Difficulty with changes in routines or environments
  4. Uneven skill development (strengths in some areas and delays in others)
  5. Unusual play with toys and other objects
  6. Repetitive body movements or behaviour patterns


The diagnosis of a pervasive developmental disorder not otherwise specified is given to individuals with difficulties in the areas of social interaction, communication, and/or stereotyped behaviour patterns or interests, but who do not meet the full criteria for autism or another PDD.

This does not necessarily mean that PDD-NOS is a milder disability than the other PDDs.


Studies suggest that persons with PDD-NOS belong to one of three very different subgroups:

  1. A high-functioning group (around 25%): Symptoms largely overlap with that of Asperger syndrome, but who differ in terms of having a lag in language development and/or mild cognitive impairment.(not a symptom in Asperger Syndrome)
  2. A group (around 25%): Symptoms more closely resemble those of Autistic Disorder, but do not fully meet all its diagnostic signs and symptoms.
  3. The biggest group (around 50%) consists of those who meet all the diagnostic criteria for Autistic Disorder, but whose stereotypical and repetitive behaviours are noticeably mild.


  1. Applied behaviour analysis
  2. Visual and environmental supports, visual schedules
  3. Discrete trial instruction (part of applied behaviour analysis)
  4. Social stories and comic strip conversations
  5. Physical and occupational therapy


Asperger Syndrome


Asperger syndrome (AS), also known as Asperger’s, is a developmental disorder characterized by significant difficulties in social interaction and nonverbal communication, along with restricted and repetitive patterns of behaviour and interests. As a milder autism spectrum disorder (ASD), it differs from other ASDs by relatively normal language and intelligence.

Signs and Symptoms

  1. Qualitative impairment in social interaction.
  2. Stereotyped and restricted patterns of behaviour, activities and interests.
  3. No clinically significant delay in cognitive development or general delay in language.
  4. Intense preoccupation with a narrow subject, one-sided verbosity, restricted prosody, and physical clumsiness.


Diagnosis is most commonly made between the ages of four and eleven. A comprehensive assessment involves a multidisciplinary team and includes neurological and genetic assessment as well as tests for cognition, psycho motor function, verbal and nonverbal strengths and weaknesses.

Conditions that must be considered in a differential diagnosis include other ASDs, the schizophrenia spectrum, ADHD, obsessive–compulsive disorder, major depressive disorder, semantic pragmatic disorder, nonverbal learning disorder, bipolar disorder, and social-cognitive deficits due to brain damage from alcohol abuse.


  1. An applied behaviour analysis (ABA) technique called social skills training for more effective interpersonal interactions.
  2. Cognitive behavioural therapy to improve stress management and to cut back on obsessive interests and repetitive routines.
  3. Medication, for coexisting conditions such as major depressive disorder and anxiety disorder.
  4. Therapy to assist with poor sensory processing and motor coordination.
  5. Social communication intervention, which is specialized speech therapy.


Childhood Disintegrative Disorder (CDD)


The childhood disintegrative disorder (CDD), also known as Heller’s syndrome and disintegrative psychosis, is a rare condition characterized by late onset of developmental delays—or stunning reversals—in language, social function, and motor skills.

CDD has some similarity to autism, and is sometimes considered a low-functioning form of is now called “regressive autism”.

Symptoms and Diagnosis

An apparent period of fairly normal development is often noted before a regression in skills or a series of regressions in skills.

The age at which this regression can occur varies, but typically after 3 years of normal development.

The regression can be so dramatic that the child may be aware of it, and may in its beginning even ask, vocally, what is happening to her/him.

Some children describe or appear to be reacting to hallucinations, but the most obvious symptom is that skills apparently attained are lost.


  1. Behavior therapy: The main aim of Applied Behavior Analysis (ABA) is to systematically teach the child to relearn language, self-care and social skills.
  2. Sensory Enrichment Therapy uses enrichment of the sensory experience to improve symptoms in autism, many of which are common to CDD.
  3. MedicationsAnti psychotic medications are used to treat aggressive stance and repetitive behaviour patterns. Anticonvulsant medications are used to control seizures.



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