Autism overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Autism is a brain development disorder that impairs social interaction and communication, and causes restricted and repetitive behavior, all starting before a child is three years old. This set of signs distinguishes autism from milder autism spectrum disorders (ASD) such as Asperger syndrome. Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by multigene interactions or by rare mutations. In rare cases, autism is strongly associated with agents that cause birth defects. Other proposed causes, such as childhood vaccines, are controversial and the vaccine hypotheses lack convincing scientific evidence. Most recent reviews estimate a prevalence of 100- 200 cases per 100,000 people for autism, and about 600 per 100,000 for ASD, with ASD averaging a 4.3:1 male-to-female ratio. The number of people known to have autism has increased dramatically since the 1980s, at least partially due to changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved. Autism affects many parts of the brain; how this occurs is poorly understood. Parents usually notice signs in the first two years of their child's life. Early behavioral or cognitive intervention can help children gain self-care, social, and communication skills. There is no cure. Few children with autism live independently after reaching adulthood, but some become successful, and an autistic culture has developed, with some seeking a cure and others believing that autism is a condition rather than a disorder.
Pathophysiology
Despite extensive investigation, how autism occurs is not well understood. Its mechanism can be divided into two areas: the pathophysiology of brain structures and processes associated with autism, and the neuropsychological linkages between brain structures and behaviors.[1] The behaviors appear to have multiple pathophysiologies.
Causes
Autism and autism spectrum disorders are complex neurodevelopmental disorders. Many causes of autism have been proposed, but its theory of causation is still incomplete.[2] Heritability contributes about 90% of the risk of a child developing autism, but the genetics of autism are complex and typically it is unclear which genes are responsible.[3] In rare cases, autism is strongly associated with agents that cause birth defects.[4] Many other causes have been proposed, such as exposure of children to vaccines; these proposals are controversial and the vaccine hypotheses have no convincing scientific evidence.[5]
Epidemiology and Demographics
Most recent reviews estimate a prevalence of 100- 200 cases per 100,000 people for autism, and about 600 per 100,000 for ASD, with ASD averaging a 4.3:1 male-to-female ratio. The number of people known to have autism has increased dramatically since the 1980s, at least partly due to changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved.
Diagnosis
History and Symptoms
Autism is distinguished by a pattern of symptoms rather than one single symptom. The main characteristics are impairments in social interaction, impairments in communication, restricted interests and repetitive behavior. Other aspects, such as atypical eating, are also common but are not essential for diagnosis. Individual symptoms of autism occur in the general population and appear not to associate highly, without a sharp line separating pathological severity from common traits.
Laboratory Findings
Clinical genetics evaluations are often done once ASD is diagnosed, particularly when other symptoms already suggest a genetic cause. Although genetic technology allows clinical geneticists to link an estimated 40% of cases to genetic causes,[6] consensus guidelines in the U.S. and UK are limited to high-resolution chromosome and fragile X testing. As new genetic tests are developed several ethical, legal, and social issues will emerge. Commercial availability of tests may precede adequate understanding of how to use test results, given the complexity of autism's genetics.[7] Metabolic tests are sometimes helpful, but are not routine.
Treatment
Medical Therapy
Many medications are used to treat problems associated with ASD.[8] More than half of U.S. children diagnosed with ASD are prescribed psychoactive drugs or anticonvulsants, with the most common drug classes being antidepressants, stimulants, and antipsychotics.[9] Aside from antipsychotics,[10] there is scant reliable research about the effectiveness or safety of drug treatments for adolescents and adults with ASD.[11] A person with ASD may respond atypically to medications, the medications can have adverse effects, and no known medication relieves autism's core symptoms of social and communication impairments.[12][13]
Behavorial Therapy
The main goals of treatment are to lessen associated deficits and family distress, and to increase quality of life and functional independence. No single treatment is best and treatment is typically tailored to the child's needs. Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills,[14] and often improve functioning and decrease symptom severity and maladaptive behaviors;[15] claims that intervention by age two to three years is crucial[16] are not substantiated.
Cost-Effectiveness of Therapy
Treatment is expensive; indirect costs are more so. A U.S. study estimated an average cost of $3.2 million in 2003 U.S. dollars for someone born in 2000, with about 10% medical care, 30% extra education and other care, and 60% lost economic productivity.[17] Publicly supported programs are often inadequate or inappropriate for a given child, and unreimbursed out-of-pocket medical or therapy expenses are associated with likelihood of family financial problems;[18] a 2008 U.S. study found a 14% average loss of annual income in families of children with ASD.[19] After childhood, key treatment issues include residential care, job training and placement, sexuality, social skills, and estate planning.[20]
References
- ↑ Penn HE (2006). "Neurobiological correlates of autism: a review of recent research". Child Neuropsychol. 12 (1): 57–79. doi:10.1080/09297040500253546. PMID 16484102.
- ↑ Trottier G, Srivastava L, Walker CD (1999). "Etiology of infantile autism: a review of recent advances in genetic and neurobiological research". J Psychiatry Neurosci. 24 (2): 103–115. PMID 10212552. Retrieved 2007-07-16.
- ↑ Freitag CM (2007). "The genetics of autistic disorders and its clinical relevance: a review of the literature". Mol Psychiatry. 12 (1): 2–22. doi:10.1038/sj.mp.4001896. PMID 17033636.
- ↑ Arndt TL, Stodgell CJ, Rodier PM (2005). "The teratology of autism". Int J Dev Neurosci. 23 (2–3): 189–99. doi:10.1016/j.ijdevneu.2004.11.001. PMID 15749245.
- ↑ Rutter M (2005). "Incidence of autism spectrum disorders: changes over time and their meaning". Acta Paediatr. 94 (1): 2–15. PMID 15858952.
- ↑ Schaefer GB, Mendelsohn NJ (2008). "Genetics evaluation for the etiologic diagnosis of autism spectrum disorders". Genet Med. 10 (1): 4–12. doi:10.1097/GIM.0b013e31815efdd7. PMID 18197051. Lay summary – Medical News Today (2008-02-07).
- ↑ McMahon WM, Baty BJ, Botkin J (2006). "Genetic counseling and ethical issues for autism". Am J Med Genet C Semin Med Genet. 142C (1): 52–7. doi:10.1002/ajmg.c.30082. PMID 16419100.
- ↑ Leskovec TJ, Rowles BM, Findling RL (2008). "Pharmacological treatment options for autism spectrum disorders in children and adolescents". Harv Rev Psychiatry. 16 (2): 97–112. doi:10.1080/10673220802075852. PMID 18415882.
- ↑ Oswald DP, Sonenklar NA (2007). "Medication use among children with autism spectrum disorders". J Child Adolesc Psychopharmacol. 17 (3): 348–55. doi:10.1089/cap.2006.17303. PMID 17630868.
- ↑ Posey DJ, Stigler KA, Erickson CA, McDougle CJ (2008). "Antipsychotics in the treatment of autism". J Clin Invest. 118 (1): 6–14. doi:10.1172/JCI32483. PMID 18172517.
- ↑ Lack of research on drug treatments:
- Angley M, Young R, Ellis D, Chan W, McKinnon R (2007). "Children and autism—part 1—recognition and pharmacological management" (PDF). Aust Fam Physician. 36 (9): 741–4. PMID 17915375.
- Broadstock M, Doughty C, Eggleston M (2007). "Systematic review of the effectiveness of pharmacological treatments for adolescents and adults with autism spectrum disorder". Autism. 11 (4): 335–48. doi:10.1177/1362361307078132. PMID 17656398.
- ↑ Template:Cite paper
- ↑ Buitelaar JK (2003). "Why have drug treatments been so disappointing?". Novartis Found Symp. 251: 235–44, discussion 245–9, 281–97. doi:10.1002/0470869380.ch14. PMID 14521196.
- ↑ Myers SM, Johnson CP, Council on Children with Disabilities (2007). "Management of children with autism spectrum disorders". Pediatrics. 120 (5): 1162–82. doi:10.1542/peds.2007-2362. PMID 17967921. Lay summary – AAP (2007-10-29).
- ↑ Rogers SJ, Vismara LA (2008). "Evidence-based comprehensive treatments for early autism". J Clin Child Adolesc Psychol. 37 (1): 8–38. doi:10.1080/15374410701817808. PMID 18444052.
- ↑ Pettus A (2008). "A spectrum of disorders". Harv Mag. 110 (3): 27–31, 89–91.
- ↑ Ganz ML (2007). "The lifetime distribution of the incremental societal costs of autism". Arch Pediatr Adolesc Med. 161 (4): 343–9. PMID 17404130. Lay summary – Harvard School of Public Health (2006-04-25).
- ↑ Sharpe DL, Baker DL (2007). "Financial issues associated with having a child with autism". J Fam Econ Iss. 28 (2): 247–64. doi:10.1007/s10834-007-9059-6.
- ↑ Montes G, Halterman JS (2008). "Association of childhood autism spectrum disorders and loss of family income". Pediatrics. 121 (4): e821–6. doi:10.1542/peds.2007-1594. PMID 18381511.
- ↑ Aman MG (2005). "Treatment planning for patients with autism spectrum disorders". J Clin Psychiatry. 66 (Suppl 10): 38–45. PMID 16401149.