Autism Spectrum Disorders - Description

Page Contents

• Other Names
• ICD-9
• Description
• Genetics
• Prognosis
• Prevalence
• Impact
• Pearls And Alerts
• Helpful Articles

Other Names

Pervasive developmental disorder, not otherwise specified (NOS)
Asperger syndrome (or disorder)

ICD-9

299.0, Autistic disorder, Infantile autism, Primary autism

299.9, Pervasive developmental disorder NOS

299.8, Other pervasive developmental disorders (Asperger disorder)

These ICD-9 Codes are for the primary diagnosis. Additional detail and codes for related diagnoses can be found in Autism ICD9 ( 77 KB) .

Description

Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders defined by qualitative impairments in communication and social interactions, restricted interests and activities, and stereotypical behaviors. Abnormalities in these three developmental areas tend to cluster together in affected individuals. All individuals with ASDs have qualitative abnormalities of social development in combination with disorders of communication and/or stereotyped repetitive interests and behaviors. The social skills that develop naturally in typically-developing children do not do so in children with ASDs. There are many behaviors and deficits that relate to each of the three domains mentioned above. As children with ASDs mature, these characteristics can change but the diagnosis remains.

ASDs are part of a larger continuum of disorders called Pervasive Developmental Disorders that also includes Rett Syndrome and Childhood Disintegrative Disorder. Autism spectrum disorders refer to Autistic disorder (AD), Pervasive developmental disorder, not otherwise specified (PDD-NOS), and Asperger syndrome (AS).

Prior to 1990, the prevalence of global developmental delay or intellectual disability among individuals with autism was estimated to be approximately 90%. More recent studies have reported rates of co-occurring intellectual disability in the range of 25-50%. Neither developmental delay nor cognitive impairment are required for an ASD diagnosis.

Individuals with ASDs may experience other cognitive, emotional, and behavioral disorders. Since these associated problems are not present in all affected individuals, they are not part of the criteria for ASDs. They do, however, occur relatively frequently, can have significant impact upon daily functioning, and are therefore important to recognize and treat.

Subtypes of autism spectrum disorders

Autistic disorder involves significant impairment in all three domains, with onset before 3 years of age. Alternative names are autism, infantile autism, primary autism. A subtype is "high-functioning autism," in which cognitive functioning is in the normal to superior range. Cognitive level in children with autism can range from profound mental retardation to superior intelligence. Verbal ability can range from absent to articulate speech.

Asperger syndrome involves significant impairments in social interaction and range of interests and activities, similar to a child with autism, but without a clinically significant delay in onset of language. Communication may be impaired by an inability to read social cues, making socially inappropriate comments, or having a narrow focus of interest. Cognitive function is within normal limits. An alternative name is Asperger's syndrome.

Pervasive developmental disorder NOS: This diagnosis is applied to the child with some characteristics of an ASD who does not meet full criteria for Autistic disorder or Asperger syndrome. Children with a diagnosis of PDD-NOS typically meet criteria for autism in the social domain and have variable impairment in the other domains. The diagnosis of PDD-NOS may apply to a child with global developmental delay who demonstrates impairment in some, but not all of the three developmental domains affected in ASD. This diagnosis may apply to individuals who meet ASD diagnostic criteria but in whom a history of language delay or regression cannot be documented. [Johnson: 2007]

Genetics

ASDs are known to be highly heritable, yet the exact cause remains unknown. They are more common in boys, with a male:female ratio of 4:1. In less than 10% of cases, ASDs are associated with a medical condition or a known syndrome such as Down syndrome, fragile X syndrome, or tuberous sclerosis. The majority of cases, however, have no clear etiology. When one sibling is affected, the recurrence risk for subsequent children is 5-6%, and higher if more than one older sibling is affected. [Schaefer: 2008]

Several genes have been associated with ASDs, and individuals with ASDs show great variation in language abilities, social skills, and behaviors. These factors suggest that autism may represent a common manifestation of multiple genetic disorders. For a comprehensive review of the genes known to be associated with ASDs, see Autism (OMIM).

Prognosis

Prognosis depends on many factors and is difficult to predict, particularly in the young child. Important factors include level of cognitive functioning, the presence of epilepsy or other medical comorbidities, joint attention skills, and functional play skills. While most children diagnosed with an ASD retain their diagnosis by age 9 years, many show considerable improvement, particularly those initially diagnosed with PDD-NOS. Favorable prognostic factors include early identification and appropriate behavioral intervention, as well as successful inclusion with typically-developing peers in mainstream educational and community settings. Poorer outcomes are associated with the presence of mental retardation, epilepsy, no functional use of language by 5 years, comorbid medical/genetic conditions, and comorbid psychiatric disorders. [National: 2001] [Johnson: 2007] [Charman: 2005] [Turner: 2006]

Prevalence

The reported prevalence of autism spectrum disorders in North America is 9/1000. Prior to 1990, the rate of autism was felt to be considerably lower (4/10000). The explanation for this increase is not clear. It may reflect changes in diagnostic criteria, as well as an increased awareness of ASDs, rather than a true increase in incidence. The increase in diagnosis of autism has occurred across the spectrum of intellectual disability. [Autism: 2009].
Limited information is available regarding the prevalence of ASD subtypes. Recent data from Canada shows an overall prevalence of 6.5/1000 for autism spectrum disorders, 2.2/1000 for Autistic Disorder, 1/1000 for Asperger Syndrome, and 3.3/1000 for PDD-NOS. [Fombonne: 2006]

Impact

Health care costs are significantly higher for children on the autism spectrum than for typically-developing children. [Croen: 2006] Regardless of the level of cognitive functioning, children on the autism spectrum who receive early, intense behavioral and educational intervention show significantly greater improvement in cognitive and adaptive functioning than those who do not. [National: 2001]

Pearls And Alerts

Helpful Articles

PubMed search for review articles on Autism in children for last 3 years.

Johnson CP, Myers SM.
Identification and evaluation of children with autism spectrum disorders.
Pediatrics. 2007;120(5):1183-215. PubMed abstract
Comprehensive clinical report addressing the definition, history, epidemiology, diagnostic criteria, early signs, neuropathologic aspects, and etiologic possibilities in autism spectrum disorders. This report also provides the primary care provider with an algorithm for assistance in the early identification of children with autism spectrum disorders.

Myers SM, Johnson CP.
Management of children with autism spectrum disorders.
Pediatrics. 2007;120(5):1162-82. PubMed abstract / Full Text
This clinical report is intended to guide clinicians toward empirically based treatments and educational strategies for children with autistic spectrum disorders.

Johnson CP.
Recognition of autism before age 2 years.
Pediatr Rev. 2008;29(3):86-96. PubMed abstract

Autism Spectrum Disorders Module Authors

The authors listed above are responsible for the overall Autism Spectrum Disorders Module. Authors contributing to individual pages in the module are listed on those pages.

Page Bibliography

Autism and Developmental Disabilities Monitoring Network Surveillance Year 2006 Principal Investigators.
Prevalence of autism spectrum disorders - Autism and Developmental Disabilities Monitoring Network, United States, 2006.
MMWR Surveill Summ. 2009;58(10):1-20. PubMed abstract

Charman T, Taylor E, Drew A, Cockerill H, Brown JA, Baird G.
Outcome at 7 years of children diagnosed with autism at age 2: predictive validity of assessments conducted at 2 and 3 years of age and pattern of symptom change over time.
J Child Psychol Psychiatry. 2005;46(5):500-13. PubMed abstract

Croen LA, Najjar DV, Ray GT, Lotspeich L, Bernal P.
A comparison of health care utilization and costs of children with and without autism spectrum disorders in a large group-model health plan.
Pediatrics. 2006;118(4):e1203-11. PubMed abstract

Fombonne E, Zakarian R, Bennett A, Meng L, McLean-Heywood D.
Pervasive developmental disorders in Montreal, Quebec, Canada: prevalence and links with immunizations.
Pediatrics. 2006;118(1):e139-50. PubMed abstract

Johnson CP, Myers SM.
Identification and evaluation of children with autism spectrum disorders.
Pediatrics. 2007;120(5):1183-215. PubMed abstract
Comprehensive clinical report addressing the definition, history, epidemiology, diagnostic criteria, early signs, neuropathologic aspects, and etiologic possibilities in autism spectrum disorders. This report also provides the primary care provider with an algorithm for assistance in the early identification of children with autism spectrum disorders.

National Research Council.
Educating Children with Autism.
1st ed. National Academies Press; 2001. 0309072697

Schaefer GB, Mendelsohn NJ.
Clinical genetics evaluation in identifying the etiology of autism spectrum disorders.
Genet Med. 2008;10(4):301-5. PubMed abstract

Turner LM, Stone WL, Pozdol SL, Coonrod EE.
Follow-up of children with autism spectrum disorders from age 2 to age 9.
Autism. 2006;10(3):243-65. PubMed abstract