Fact sheet on classification and diagnosis of Autism, an Autism Spectrum Disorder


The classification and diagnosis of autism, Aspergers syndrome and other related disorders is constantly changing, and is increasingly the subject of much discussion and dispute.


The manifestations of these disorders cover a wide spectrum, ranging from individuals with severe impairments—who may be silent, mentally disabled, and locked into hand flapping and rocking—to less impaired individuals who may have active but distinctly odd social approaches, narrowly focused interests, and verbose, pedantic communication.


Although there are various diagnostic frameworks available, the most common to date is the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Part of the confusion around classifying these disorders is that the characteristics vary so widely from child to child. There has been an trend to refer to children and adults being on the 'autism spectrum', a term coming into wider international usage. The fact sheets on this site will use this term frequently.


Pervasive Developmental Disorders (PDD)

The term Pervasive Developmental Disorders, or PDD, has been in use for many years and has been the traditionally accepted way to group disorders such as autism and Asperger's syndrome. This came about because the most common tool used for diagnosis, the Diagnostic and Statistical Manual of Mental Disorders, uses this framework. The DSM-IV has evolved over time and the fourth issue includes autism and Asperger's syndrome in a group of five disorders called Pervasive Developmental Disorders:


Pervasive Developmental Disorders – Autism, Aspergers Syndrome, Rett's Disorder, PDD-NOS, and Childhood Disintegrative Disorder


Of the other four PDD forms, Asperger syndrome is closest to autism in signs and likely causes; Rett Syndrome and childhood disintegrative disorder share several signs with autism, but may have unrelated causes; PDD not otherwise specified (PDD-NOS) is diagnosed when the criteria are not met for a more specific disorder. Unlike autism, Asperger's has no substantial delay in language development.


Autism Spectrum Disorders (ASD)

There has been much discussion on this system of classification and there has been an increasing move to see some of these disorders as being placed on a spectrum. Autism is typically called Autistic Disorder under this classification, although this website still uses the term "autism" as it is the most common terminology in use. Autism is grouped with Asperger's syndrome and two other disorders as the Autism Spectrum Disorders. or Autism Spectrum Disorders:


Autism, Aspergers Syndrome, high functioning autism, pdd-nos


While the DSM-IV does not portray this classification, it may incorporated into a future edition. The term 'Autism Spectrum Disorder' or ASD, is being adopted widely, along with referring to a child or adult as being 'on the autism spectrum'. For those who follow this system, there is some debate over whether high-functioning autism is simply Aspergers syndrome. This website is simply intended to provide practical information and tips for parents, friends, teachers, employers and the wider community, so these debates will not feature strongly on this site.


The terminology of autism can be bewildering, with autism, Asperger's and PDD-NOS often called the Autism Spectrum Disorders (ASD) or sometimes the autistic disorders, whereas autism itself is often called autistic disorder, childhood autism, or infantile autism. Sometimes people use the term 'autism' to refer to autistic disorders or to Autism Spectrum Disorders, or equate Autism Spectrum Disorder with PDD. Autism Spectrum Disorder, in turn, is a subset of the broader autism phenotype (BAP), which describes individuals who may not have Autism Spectrum Disorder but do have autistic-like traits, such as avoiding eye contact.


Differences between aspergers syndrome & high-functioning autism

Although individuals with Asperger's syndrome tend to perform better cognitively than those with autism, the extent of the overlap between Aspergers syndrome and high-functioning autism is unclear.


A neuropsychological profile has been proposed for Aspergers syndrome; if verified, it could differentiate between Aspergers syndrome and high-functioning autism and aid in differential diagnosis. Relative to high-functioning autism, people with Aspergers syndrome have deficits in nonverbal skills such as visual-spatial problem solving and visual-motor coordination, along with stronger verbal abilities. Several studies have found Aspergers syndrome with a neuropsychologic profile of assets and deficits consistent with a nonverbal learning disability, but several other studies have failed to replicate this. The literature review did not reveal consistent findings of "nonverbal weaknesses or increased spatial or motor problems relative to individuals with high-functioning autism", leading some researchers to argue that increased cognitive ability is evidenced in Aspergers syndrome relative to high-functioning autism regardless of differences in verbal and nonverbal ability.


Aspergers syndrome may also be called Asperger syndrome, Asperger's syndrome or simply Asperger's. It is hoped we are moving to an internationally recognized system that will provide consistency for everyone. For parents though, the key will be practical strategies that help to minimize their child's developmental delays and provide a better future - these strategies still apply despite where researchers set the fence posts for classifying your child's position on the autism spectrum.


This website focuses on Asperger's syndrome and autism (or Autistic Disorder). To suit an international audience, these fact sheets will refer to both Autism Spectrum Disorders and Pervasive Developmental Disorders and use various terms more or less interchangeably.


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This autism fact sheet is licensed under the GNU Free Documentation. It is derivative of an autism and Asperger's syndrome-related articles at http://en.wikipedia.org

Trying to sort out the different terms surrounding Autism can be a real headache! This fact sheet attempts to make sense of Autism, Asperger's, the autism spectrum, and other developmental disorders