II. Definitions
Autism and Related Conditions

Other conditions may be associated with autism in one or more of the following ways:

  • Autistic Spectrum Disorders (Pervasive Developmental Disorders) all share some features in common. Often, other PDDs are considered variant forms of autism rather than completely separate conditions.
    e.g. Asperger Syndrome
  • Autistic behaviours may be mis-diagnosed as being the result of another condition.
    e.g. Personality Disorder
  • The behaviours of another condition may be mis-diagnosed as autism.
    e.g. Landau Kleffner Syndrome
  • The condition may be co-morbid with (occur in the same person at the same time) autism.
    e.g. Depression

In most cases, a Pervasive Developmental Disorder is the primary diagnosis, with secondary ones only being warranted if the symptoms are very severe and outside of the range normally accounted for by the PDD. For example, people with Asperger Syndrome tend to be clumsy, so coordination problems are considered part of the AS, and a diagnosis of co-morbid Dyspraxia is not usually warranted. The same situation occurs frequently with ADD/ADHD, Sensory Integration Dysfunction, and OCD and less frequently with most of the other conditions in this section.


  1. Pervasive Developmental Disorders (Autistic Spectrum Disorders)
    Definition and description of conditions on the autistic spectrum.
    1. Autistic Disorder
    2. Asperger Syndrome
    3. Childhood Disintegrative Disorder
    4. Rett Syndrome
    5. Pervasive Developmental Disorder Not Otherwise Specified
  2. Mental Health and Behaviour Disorders:
    Common mis-diagnoses and Co-morbid Conditions (especially for High Functioning autistics)
    1. Personality disorders
    2. Schizophrenia
    3. Obsessive-Compulsive Disorder (OCD)
    4. Attention Deficit (Hyperactivity) Disorder (ADHD)
    5. Oppositional Defiant Disorder (ODD)
    6. Mood Disorders (Bipolar Disorder and Depression)
    7. Psychoneuroses (neurosis)
  3. Genetic and Other Syndromes
    Autism-like conditions and syndromes that sometimes co-morbid with ASDs
    1. Fragile X
    2. Down Syndrome
    3. Landau Kleffner Syndrome
    4. Angelman Syndrome
    5. Other Syndromes
  4. Motor and Sensory Disorders
    1. Dyspraxia/Apraxia/Developmental Coordination Disorder
    2. Tourette Syndrome
    3. Central Auditory Processing Disorder, CAPD
    4. Sensory Integration Dysfunction, SID
    5. Scotopic Sensitivity Syndrome ("Irlen Syndrome"), SSS
    6. Other Sensory Conditions
  5. Language Disorders and Specific Learning Disabilities
    1. Dyslexia
    2. Semantic-Pragmatic Disorder
    3. Hyperlexia
    4. Verbal Dyspraxia/Apraxia
    5. Non-verbal Learning Disability
  6. Food Intolerances and Coeliac Disease
    1. Lactose Intolerance
    2. Casein Intolerance
    3. Gluten Intolerance and Coeliac Disease

See also:


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Originally compiled by Anna Hayward on behalf of the alt.support.autism newsgroup, November 2000. Original site design and HTML by Kalen Molton. Please address any general queries to Mike Stanton. Broken links and problems of a technical nature should be addressed to John Muggleton by entering details in the comments box of the form here. Any opinions expressed in this article are personal and should not be construed as medical advice. We are not representatives of any of the companies discussed, nor do we receive any form of commission.

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