Autism differential diagnosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Differentiating Autism from Other Disorders
Diagnosis is based on behavior, not cause or mechanism.[1][2] Autism is defined in the DSM-IV-TR as exhibiting at least six symptoms total, including at least two symptoms of qualitative impairment in social interaction, at least one symptom of qualitative impairment in communication, and at least one symptom of restricted and repetitive behavior. Sample symptoms include lack of social or emotional reciprocity, stereotyped and repetitive use of language or idiosyncratic language, and persistent preoccupation with parts of objects. Onset must be prior to age three years, with delays or abnormal functioning in either social interaction, language as used in social communication, or symbolic or imaginative play. The disturbance must not be better accounted for by Rett syndrome or childhood disintegrative disorder.[3] ICD-10 uses essentially the same definition.[4]
Several diagnostic instruments are available. Two are commonly used in autism research: the Autism Diagnostic Interview-Revised (ADI-R) is a semistructured parent interview, and the Autism Diagnostic Observation Schedule (ADOS) uses observation and interaction with the child. The Childhood Autism Rating Scale (CARS) is used widely in clinical environments to assess severity of autism based on observation of children.[5]
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 other factors using standardized tools, and taking into account any associated medical conditions. A differential diagnosis for ASD at this stage might also consider mental retardation, hearing impairment, and a specific language impairment[6] such as Landau-Kleffner syndrome.[7] ASD can sometimes be diagnosed by age 14 months, although diagnosis becomes increasingly stable over the first three years of life: for example, a one-year-old who meets diagnostic criteria for ASD is less likely than a three-year-old to continue to do so a few years later.[8] In the UK the National Autism Plan for Children recommends at most 30 weeks from first concern to completed diagnosis and assessment, though few cases are handled that quickly in practice.[6] A 2006 U.S. study found the average age of first evaluation by a qualified professional was 48 months and of formal ASD diagnosis was 61 months, reflecting an average 13-month delay, all far above recommendations.[9]
References
- ↑ London E (2007). "The role of the neurobiologist in redefining the diagnosis of autism". Brain Pathol. 17 (4): 408–11. doi:10.1111/j.1750-3639.2007.00103.x. PMID 17919126.
- ↑ Baird G, Cass H, Slonims V (2003). "Diagnosis of autism". BMJ. 327 (7413): 488–93. doi:10.1136/bmj.327.7413.488. PMID 12946972.
- ↑ American Psychiatric Association (2000). "Diagnostic criteria for 299.00 Autistic Disorder". Diagnostic and Statistical Manual of Mental Disorders (4th ed., text revision (DSM-IV-TR) ed.). ISBN 0890420254. Retrieved 2007-06-25.
- ↑ World Health Organization (2006). "F84. Pervasive developmental disorders". International Statistical Classification of Diseases and Related Health Problems (10th ed. (ICD-10) ed.). Retrieved 2007-06-25.
- ↑
- ↑ 6.0 6.1 Dover CJ, Le Couteur A (2007). "How to diagnose autism". Arch Dis Child. 92 (6): 540–5. doi:10.1136/adc.2005.086280. PMID 17515625.
- ↑ Mantovani JF (2000). "Autistic regression and Landau-Kleffner syndrome: progress or confusion?". Dev Med Child Neurol. 42 (5): 349–53. doi:10.1111/j.1469-8749.2000.tb00104.x. PMID 10855658.
- ↑ Landa RJ (2008). "Diagnosis of autism spectrum disorders in the first 3 years of life". Nat Clin Pract Neurol. 4 (3): 138–47. doi:10.1038/ncpneuro0731. PMID 18253102.
- ↑ Wiggins LD, Baio J, Rice C (2006). "Examination of the time between first evaluation and first autism spectrum diagnosis in a population-based sample". J Dev Behav Pediatr. 27 (2 Suppl): S79–87. PMID 16685189.