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What is Autism Spectrum Disorder?

Autism Spectrum Disorder is diagnosed based on strict criteria set forth in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV; APA, 1994). It is listed under the category of Pervasive Development Disorder (PDD).

 

There are four types of Autism Spectrum Disorders 

  • Autism (formally mistakenly referred to as Infantile Shizophrenia)
  • Aspergers Syndrome (also known as high-functioning ASD)
  • Retts Syndrome
  • PDD-NOS (not otherwise specified, also known as atypical autism)

Over the past two decades, the rate of autism has increased from 3.3 cases in 10,000 in the 1980's  to between 55-70 cases per 10,000 recently (as many as 1 in 200 births for autism and 1 in 150 births for all types of Autistic Spectrum Disorder). 

 

Although it is now a relatively common neuro-developmental disability, Autism Spectrum Disorder is often very difficult to diagnose. ASD is marked by a triad of symptoms; repetitive or ritualistic behaviours, lack of or inappropriate social interaction, and language delays. 


Currently, there is no known cure for autism, simply because there is no known 'singular cause'. However, there is some evidence of abnormalities in the x-chromosome and chromosomes 7 and 15, suggesting a genetic component to the development of the disorder. 

 

Treatment of the symptoms of autism can be more effective if intensive skill training is begun immediately. Thus early diagnosis is helpful.

 

Diagnostic Criteria for Autism (DSM-IV-TR)

 

Qualitative Impairment in Social Interactions

·       Impairment in non-verbal behaviours (eye gaze, posture, facial expression, & gestures)

             ·        Failure to develop peer relationships appropriate to developmental level 

·        Lack of spontaneous seeking to share interests/achievements 

·        Lack social/emotional reciprocity                           


Restricted, repetitive, & stereotyped behaviours, interests, and activities

·        Preoccupation with restricted, stereotyped interest, of abnormal intensity or focus 

·        Inflexible adherence to specific, non-functional routines or rituals 

·        Stereotyped/repetitive motor mannerism 

·        Persistent preoccupation with parts of objects  

 

Qualitative Impairment in Communication

·        Delay in or total lack of spoken language 

·        If adequate speech, then impaired ability to initiate or sustain conversation 

·        Stereotyped and repetitive use of language/idiosyncratic language 

·        Lack of varied, spontaneous pretend play or social imitative play


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Asperger's Syndrome


Asperger's Syndrome is characterised by severe and sustained impairment in social interaction, development of restricted and repetitive patterns of behaviour, interests, and activities. These characteristics result in clinically significant impairment in social, occupational, or other important areas of functioning. In contrast to Autism, there are no clinically significant delays in language or cognition or self-help skills or in adaptive behaviour, other than social interaction. Those with AS have normal IQ and their expressive vocabularies may be extraordinarily rich. Often these children are referred to as "little professors". However, they are inclined to take almost everything in its literal sense, have deficits in pragmatics and prosody, and difficulty using language in a social context

 

Diagnostic Criteria for Aspergers Syndrome (DSM-IV-TR)

  • Qualitative impairment in social interaction
  • Restricted repetitive and stereotyped patterns of behavior, interests, and activities,
  • The disturbance causes clinically significant impairment in social, occupational, or other important areas of functioning
  • There is no clinically significant general delay in language (e.g., single words used by age 2 years, communicative phrases used by age 3 years)
  • There is no clinically significant delay in cognitive development or in the development of age-appropriate self-help skills, adaptive behavior (other than social interaction), and curiosity about the environment in childhood
  • Criteria are not met for another specific Pervasive Developmental Disorder or Schizophrenia


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Rett Syndrome 


Rett Syndrome is a neurological disorder, often misdiagnosed as autism, cerebral palsy or non-specified developmental delay. It is caused by a defective regulatory MECP2 gene found on the X chromosome and is almost seen exclusively in females.

Development appears normal until 6-18 months of age  but this is followed by a gradual loss of acquired speech and hand skills, slowing of head growth, development of stereotyped repetitive hand movements, and loss or difficulty with mobility. Hand movements including handwashing, hand wringing, hand tapping, hand clapping, hand mouthing  are seen. These hand movements may change over time but will generally interfere with functional use of hands.

 

Diagnostic Criteria for Rett Syndrome (DSM-IV-TR)

  • apparently normal prenatal and perinatal history

  • psychomotor development largely normal through the first six months or may be delayed  from birth

  • normal head circumference at birth

  • postnatal deceleration of head growth

  • loss of achieved purposeful hand skill between ages ½ - 2½ years

  • stereotypic hand movements such as hand wringing/squeezing, clapping/tapping, mouthing and washing/rubbing automatisms

  • emerging social withdrawal, communication dysfunction, loss of learned words, and cognitive impairment

  • impaired movement (dyspraxia) or failing locomotion (also seen as wide-gait or unbalanced gait)

Supportive criteria

  • awake disturbances of breathing (hyperventilation, breath-holding, forced expulsion of air or saliva, air swallowing)

  • bruxism (teeth grinding)

  • impaired sleep pattern from early infancy

  • abnormal muscle tone (hypotonia) successively associated with muscle wasting and dystonia

  • peripheral vasomotor disturbances (related to the dilation and constriction of muscles and nerves that regulate blood flow)

  • scoliosis/kyphosis progressing through childhood

  • growth retardation (small for age)

  • hypotrophic (small) and cold feet; small, thin hands

Exclusion criteria

  • organomegaly or other signs of storage disease

  • retinopathy, optic atrophy, or cataract

  • evidence of perinatal or postnatal brain damage

  • existence of identifiable metabolic or other progressive neurological disorder

  • acquired neurological disorder resulting from severe infections or head trauma