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| − | [[Category:Politics and social sciences]]
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| − | [[Category:Psychology]]
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| − | {{Infobox_Disease
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| − | | Name = Autism
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| − | | Image = Autism-stacking-cans_edit.jpg
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| − | | Caption = Obsessively stacking or lining up objects may indicate autism.
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| − | | DiseasesDB = 1142
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| − | | ICD10 = {{ICD10|F|84|0|f|80}}
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| − | | ICD9 = {{ICD9|299.0}}
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| − | | ICDO =
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| − | | OMIM = 209850
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| − | | MedlinePlus = 001526
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| − | | eMedicineSubj = med
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| − | | eMedicineTopic = 3202
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| − | | eMedicine_mult = {{eMedicine2|ped|180}}
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| − | | MeshID = D001321
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| − | }}
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| − | '''Autism''' is a [[Neurodevelopmental disorder|brain development disorder]] characterized by impairments in social interaction and communication, and restricted and repetitive behavior, all exhibited before a child is three years old. These characteristics distinguish autism from milder [[autism spectrum disorders]] (ASD).
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| − | [[Heritability]] contributes about 90% of the risk of a child's developing the disorder, although the [[Heritability of autism|genetics of autism]] are complex, and it is generally unclear which genes are responsible.<ref name=Freitag/> In rare cases, autism is strongly associated with [[Teratology|agents]] that cause birth defects.<ref name=Arndt/> Other proposed [[Causes of autism|causes]], such as the exposure of children to vaccines, are [[Controversies in autism|controversial]] and the vaccine hypotheses are unsupported by convincing [[Evidence-based medicine|scientific evidence]].<ref name=Rutter/> Most recent reviews estimate a [[prevalence]] of one to two cases per 1,000 people for autism, and about six per 1,000 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 prevalence has increased is unresolved.<ref name=Newschaffer/>
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| − | Autism affects many parts of the brain; how this occurs is poorly understood. Parents usually notice signs in the first year or two of their child's life. Early intervention may help children gain self-care and social skills, although few of these interventions are supported by scientific studies; there is no cure.<ref name=Francis/> With severe autism, independent living is unlikely; with milder autism, there are some success stories for adults,<ref name=Howlin/> and an [[Sociological and cultural aspects of autism|autistic culture]] has developed, with some seeking a cure and others believing that autism is a condition rather than a disorder.<ref name=Rajendran/>
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| − | ==Classification==
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| − | Autism is a [[developmental disorder]] of the [[human brain]] that first shows signs during infancy or childhood and follows a steady course without [[Remission (medicine)|remission]] or [[relapse]].<ref name=ICD-10-F84.0/> Impairments result from maturation-related changes in various systems of the brain.<ref name=Penn/> Autism is one of the five [[pervasive developmental disorder]]s (PDD) or [[autism spectrum disorder]]s (ASD), which are characterized by widespread abnormalities of social interactions and communication, and severely restricted interests and highly repetitive behavior.<ref name=ICD-10-F84.0/>
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| − | Of the other four autism spectrum disorders, [[Asperger's 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-NOS|pervasive developmental disorder not otherwise specified (PDD-NOS)]] is diagnosed when the criteria are not met for a more specific disorder.<ref>{{cite journal|author=Lord C, Cook EH, Leventhal BL, [[David Amaral|Amaral DG]]|title=Autism spectrum disorders|journal=Neuron|volume=28|issue=2|date=2000|pages=355–63|doi=10.1016/S0896-6273(00)00115-X|pmid=11144346|url=http://download.neuron.org/pdfs/0896-6273/PIIS089662730000115X.pdf|format=PDF}}</ref> Unlike autism, Asperger's has no substantial delay in [[language development]].<ref>{{cite book|title=Diagnostic and Statistical Manual of Mental Disorders|edition=4th ed., text revision ([[DSM-IV-TR]])|author=[[American Psychiatric Association]]|date=2000|isbn=0890420254|chapter=Diagnostic criteria for 299.80 Asperger's Disorder (AD)|chapterurl=http://www.behavenet.com/capsules/disorders/asperger.htm|accessdate=2007-06-28}}</ref> The terminology of autism can be bewildering, with autism, Asperger's and PDD-NOS sometimes called the ''autistic disorders'',<ref name=Freitag>{{cite journal|author=Freitag CM|title=The genetics of autistic disorders and its clinical relevance: a review of the literature|journal=Mol Psychiatry|volume=12|issue=1|pages=2–22|date=2007|doi=10.1038/sj.mp.4001896|pmid=17033636|url=http://www.nature.com/mp/journal/v12/n1/full/4001896a.html}}</ref> whereas autism itself is often called ''autistic disorder'', ''childhood autism'', or ''infantile autism''. In this article, ''autism'' refers to the classic autistic disorder, while other sources sometimes use ''autism'' to refer to autistic disorders or even ASD. ASD, in turn, is a subset of the broader autism [[phenotype]] (BAP), which describes individuals who may not have ASD but do have autistic-like [[Trait (biology)|traits]], such as avoiding eye contact.<ref>{{cite journal|author=Piven J, Palmer P, Jacobi D, Childress D, Arndt S|title=Broader autism phenotype: evidence from a family history study of multiple-incidence autism families|journal=Am J Psychiatry|date=1997|volume=154|issue=2|pages=185–90|pmid=9016266|url=http://ajp.psychiatryonline.org/cgi/reprint/154/2/185.pdf|format=PDF}}</ref>
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| − | Autism's manifestations cover a wide spectrum, ranging from individuals with severe impairments—who may be silent, [[Developmental Disability|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.<ref>{{cite journal|author=Happé F|title=Understanding assets and deficits in autism: why success is more interesting than failure |journal=Psychologist |volume=12 |issue=11 |pages=540–47 |date=1999|url=http://www.bps.org.uk/publications/thepsychologist/search-the-psychologist-online.cfm?fuseaction=inc_getFile&ID=133&Publication_ID=1|format=PDF}}</ref> Sometimes the syndrome is divided into low-, medium- and [[high-functioning autism]] (LFA, MFA, and HFA), based on [[IQ]] thresholds,<ref name=hypersystem/> or on how much support the individual requires in daily life; these subdivisions are not standardized and are [[Controversies about functioning labels in the autism spectrum|controversial]]. Autism can also be divided into [[syndrome|syndromal]] and non-syndromal autism, where the former is associated with severe or profound [[mental retardation]] or a congenital syndrome with physical symptoms, such as [[tuberous sclerosis]].<ref name=Cohen>{{cite journal|journal=J Autism Dev Disord|date=2005|volume=35|issue=1|pages=103–16|title=Specific genetic disorders and autism: clinical contribution towards their identification|author=Cohen D, Pichard N, Tordjman S ''et al.''|doi=10.1007/s10803-004-1038-2|pmid=15796126}}</ref> Although individuals with Asperger's tend to perform better cognitively than those with autism, the extent of the overlap between Asperger's, HFA, and non-syndromal autism is unclear.<ref>Autism and Asperger's:
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| − | *{{cite book |author= [[Eric Schopler|Schopler E]], Mesibov GB, Kunce LJ (eds) |title= Asperger syndrome or high-functioning autism? |year=1998 |publisher=Springer |isbn=0306457466}}
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| − | *{{cite journal |journal= Rev Bras Psiquiatr |year=2006 |volume=28 |issue=Suppl 1 |pages=S3–S11 |title= Autism and Asperger syndrome: an overview |author= Klin A |pmid=16791390 |url=http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-44462006000500002&lng=en&nrm=iso&tlng=en}}</ref>
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| − | Some studies have reported diagnoses of autism in children due to a loss of language or social skills, as opposed to a failure to make progress. Several terms are used for this phenomenon, including [[regressive autism]], setback autism, and developmental stagnation. The validity of this distinction remains controversial; it is possible that regressive autism is a specific subtype.<ref name=Landa/><ref name=Volkmar>{{cite journal|author=Volkmar F, Chawarska K, Klin A|title=Autism in infancy and early childhood|journal=Annu Rev Psychol|date=2005|volume=56|pages=315–36|doi=10.1146/annurev.psych.56.091103.070159|pmid=15709938}}</ref>
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| − | ==Characteristics==
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| − | 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.<ref name=Filipek/>
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| − | ===Social development===
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| − | Autistic people have social impairments and often lack the intuition about others that many people take for granted. Noted autistic [[Temple Grandin]] described her inability to understand the social communication of [[neurotypical]]s as leaving her feeling "like an anthropologist on Mars".<ref>{{cite book|title=[[An Anthropologist on Mars]]: Seven Paradoxical Tales|author=[[Oliver Sacks|Sacks O]]|publisher=Knopf|date=1995|isbn=0679437851}}</ref>
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| − | Social impairments become apparent early in childhood and continue through adulthood. Autistic infants show less attention to social stimuli, smile and look at others less often, and respond less to their own name. Autistic toddlers have more striking social deviance; for example, they have less [[eye contact]] and anticipatory postures and are less likely to use another person's hand or body as a tool.<ref name=Volkmar/> Three- to five-year-old autistic children are less likely to exhibit social understanding, approach others spontaneously, imitate and respond to emotions, communicate nonverbally, and take turns with others. However, they do form [[Attachment (psychology)|attachments]] to their primary caregivers.<ref>{{cite journal|journal=Ment Retard Dev Disabil Res Rev|date=2004|volume=10|issue=4|pages=221–33|title=Early detection of core deficits in autism|author=Sigman M, Dijamco A, Gratier M, Rozga A|doi=10.1002/mrdd.20046|pmid=15666338}}</ref> They display moderately less [[Attachment in children#Secure attachment|attachment security]] than usual, although this feature disappears in children with higher mental development or less severe ASD.<ref>{{cite journal|journal=J Child Psychol Psychiatry|date=2004|volume=45|issue=6|pages=1123–34|title=Autism and attachment: a meta-analytic review|author=Rutgers AH, Bakermans-Kranenburg MJ, van IJzendoorn MH, van Berckelaer-Onnes IA|doi=10.1111/j.1469-7610.2004.t01-1-00305.x|pmid=15257669}}</ref> Older children and adults with ASD perform worse on tests of face and emotion recognition.<ref name=Sigman>{{cite journal |journal= Annu Rev Clin Psychol |year=2006 |volume=2 |pages=327–55 |title= Autism from developmental and neuropsychological perspectives |author= Sigman M, Spence SJ, Wang AT |doi=10.1146/annurev.clinpsy.2.022305.095210 |pmid=17716073}}</ref>
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| − | Contrary to common belief, autistic children do not prefer to be alone. Making and maintaining friendships often proves to be difficult for those with autism. For them, the quality of friendships, not the number of friends, predicts how lonely they are.<ref name=Burgess/>
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| − | There are many anecdotal reports, but few systematic studies, of aggression and violence in individuals with ASD. The limited data suggest that in children with mental retardation, autism is associated with aggression, destruction of property, and tantrums. Dominick ''et al.'' interviewed the parents of 67 children with ASD and reported that about two-thirds of the children had periods of severe tantrums and about one third had a history of aggression, with tantrums significantly more common than in children with a history of language impairment.<ref name=Dominick/>
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| − | ===Communication===
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| − | About a third to a half of individuals with autism do not develop enough natural speech to meet their daily communication needs.<ref>{{cite journal|journal=J Intellect Disabil Res|date=2006|volume=50|issue=9|pages=621–32|title=The ComFor: an instrument for the indication of augmentative communication in people with autism and intellectual disability|author=Noens I, van Berckelaer-Onnes I, Verpoorten R, van Duijn G|doi=10.1111/j.1365-2788.2006.00807.x|pmid=16901289}}</ref> Differences in communication may be present from the first year of life, and may include delayed onset of [[babbling]], unusual gestures, diminished responsiveness, and the desynchronization of vocal patterns with the caregiver. In the second and third years, autistic children have less frequent and less diverse babbling, consonants, words, and word combinations; their gestures are less often integrated with words. Autistic children are less likely to make requests or share experiences, and are more likely to simply repeat others' words ([[echolalia]])<ref name=Landa/><ref name=Tager-Flusberg/> or [[Pronoun reversal|reverse pronouns]].<ref name=Kanner1943/> Autistic children may have difficulty with imaginative play and with developing symbols into language.<ref name=Landa>{{cite journal|journal=Ment Retard Dev Disabil Res Rev|date=2007|volume=13|issue=1|pages=16–25|title=Early communication development and intervention for children with autism|author=Landa R|doi=10.1002/mrdd.20134|pmid=17326115}}</ref><ref name=Tager-Flusberg>{{cite journal |journal=Pediatr Clin North Am |year=2007 |volume=54 |issue=3 |pages=469–81 |title=Language disorders: autism and other pervasive developmental disorders |author= Tager-Flusberg H, Caronna E |doi=10.1016/j.pcl.2007.02.011 |pmid=17543905}}</ref> They are more likely to have problems understanding pointing; for example, they may look at a pointing hand instead of the pointed-at object.<ref name=Volkmar/><ref name=Tager-Flusberg/>
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| − | In a pair of studies, high-functioning autistic children aged 8–15 performed equally well, and adults better than individually matched controls at basic language tasks involving vocabulary and spelling. Both autistic groups performed worse than controls at complex language tasks such as figurative language, comprehension and inference. As people are often sized up initially from their basic language skills, these studies suggest that people speaking to autistic individuals are more likely to overestimate what their audience comprehends.<ref name=Williams/>
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| − | ===Repetitive behavior===
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| − | [[Image:Autistic-sweetiepie-boy-with-ducksinarow.jpg|thumb|A young boy with autism, and the precise line of toys he made]]
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| − | Autistic individuals display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (RBS-R) categorizes as follows.
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| − | *'''[[Stereotypy (psychiatry)|Stereotypy]]''' is apparently purposeless movement, such as hand flapping, head rolling, body rocking, or spinning a plate.
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| − | *'''[[OCD|Compulsive behavior]]''' is intended and appears to follow rules, such as arranging objects in a certain way.
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| − | *'''Sameness''' is resistance to change; for example, insisting that the furniture not be moved or refusing to be interrupted.
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| − | *'''[[Ritual#Psychology|Ritualistic behavior]]''' involves the performance of daily activities the same way each time, such as an unvarying menu or dressing ritual.
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| − | *'''Restricted behavior''' is limited in focus, interest, or activity, such as preoccupation with a single television program.
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| − | *'''[[Self-injury]]''' includes movements that injure or can injure the person, such as biting oneself. Dominick ''et al.'' reported that self-injury at some point affected about 30% of children with ASD.<ref name=Dominick/>
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| − | No single repetitive behavior is associated with autism, but only autism appears to have an elevated pattern of occurrence and severity of these behaviors.<ref>{{cite journal|journal=J Autism Dev Disord|date=2000|volume=30|issue=3|pages=237–43|title=Varieties of repetitive behavior in autism: comparisons to mental retardation|author=Bodfish JW, Symons FJ, Parker DE, Lewis MH|doi=10.1023/A:1005596502855|pmid=11055459}}</ref>
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| − | ===Other symptoms===
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| − | Autistic individuals may have symptoms that are independent of the diagnosis, but that can affect the individual or the family.<ref name=Filipek>{{cite journal|author=Filipek PA, Accardo PJ, Baranek GT ''et al.''|title=The screening and diagnosis of autistic spectrum disorders|journal=J Autism Dev Disord|date=1999|volume=29|issue=6|pages=439–84| doi=10.1023/A:1021943802493}} Erratum (2000). ''J Autism Dev Disord'' '''30''' (1): 81. {{doi|10.1023/A:1017256313409}}. PMID 10638459. This paper represents a consensus of representatives from nine professional and four parent organizations in the U.S.</ref>
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| − | As many as 10% of individuals with ASD show unusual abilities, ranging from splinter skills such as the memorization of trivia to the extraordinarily rare talents of prodigious [[autistic savant]]s.<ref>{{cite web|author=Treffert DA|title=Savant syndrome: an extraordinary condition|publisher=Wisconsin Medical Society|date=2007|url=http://www.wisconsinmedicalsociety.org/savant_syndrome/overview_of_savant_syndrome/synopsis|accessdate=2007-07-13}}</ref>
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| − | Unusual responses to [[Stimulus (physiology)|sensory stimuli]] are more common and prominent in autistic children, although there is no good evidence that sensory symptoms differentiate autism from other developmental disorders.<ref>{{cite journal|journal=J Child Psychol Psychiatry|date=2005|volume=46|issue=12|pages=1255–68|title=Annotation: what do we know about sensory dysfunction in autism? A critical review of the empirical evidence|author=Rogers SJ, Ozonoff S|doi=10.1111/j.1469-7610.2005.01431.x|pmid=16313426}}</ref> The responses may be more common in children: a pair of studies found that autistic children had impaired [[Tactition|tactile perception]] while autistic adults did not. The same two studies also found that autistic individuals had more problems with complex memory and reasoning tasks such as [[Twenty Questions]]; these problems were somewhat more marked among adults.<ref name=Williams/>
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| − | Several studies have reported associated motor problems that include [[poor muscle tone]], [[Apraxia|poor motor planning]], and [[toe walking]]; ASD is not associated with severe motor disturbances.<ref>{{cite journal|journal=Brain Dev|date=2007|title=Prevalence of motor impairment in autism spectrum disorders|author=Ming X, Brimacombe M, Wagner GC|doi=10.1016/j.braindev.2007.03.002|pmid=17467940}}</ref>
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| − | Atypical eating behavior occurs in about three-quarters of children with ASD, to the extent that it was formerly a diagnostic indicator. Selectivity is the most common problem, although eating rituals and food refusal also occur;<ref name=Dominick/> this does not appear to result in [[malnutrition]]. Some children with autism also have [[gastrointestinal]] (GI) symptoms, but there is a lack of published rigorous data to support the theory that autistic children have more or different GI symptoms than usual.<ref>{{cite journal|journal=J Autism Dev Disord|date=2005|volume=35|issue=6|pages=713–27|title=Gastrointestinal factors in autistic disorder: a critical review|author=Erickson CA, Stigler KA, Corkins MR, Posey DJ, Fitzgerald JF, McDougle CJ|doi=10.1007/s10803-005-0019-4|pmid=16267642}}</ref>
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| − | [[Sleep]] problems are known to be more common in children with developmental disabilities, and there is some evidence that children with ASD are more likely to have even more sleep problems than those with other developmental disabilities; autistic children may experience problems including difficulty in falling asleep, frequent nocturnal [[Wakefulness|awakenings]], and early morning awakenings. Dominick ''et al.'' found that about two-thirds of children with ASD had a history of sleep problems.<ref name=Dominick>{{cite journal|journal=Res Dev Disabil|year=2007|volume=28|issue=2|pages=145–62|title=Atypical behaviors in children with autism and children with a history of language impairment|author=Dominick KC, Davis NO, Lainhart J, Tager-Flusberg H, Folstein S|doi=10.1016/j.ridd.2006.02.003|pmid=16581226}}</ref>
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| − | ==Causes==
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| − | {{main|Causes of autism}}
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| − | Although many genetic and environmental causes of autism have been proposed, its [[Etiology|theory of causation]] is still incomplete.<ref>{{cite journal|author=Trottier G, Srivastava L, Walker CD|title=Etiology of infantile autism: a review of recent advances in genetic and neurobiological research|journal=J Psychiatry Neurosci|date=1999|volume=24|issue=2|pages=103–15|pmid=10212552|url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?pubmedid=10212552}}</ref> Some researchers argue this is because autism is not a single disorder, but rather a triad of core aspects (social impairment, communication difficulties, and repetitive behaviors) that have distinct causes but often co-occur.<ref name=HappeTime>{{cite journal|author=Happé F, Ronald A, Plomin R|title=Time to give up on a single explanation for autism|journal=Nat Neurosci|date=2006|volume=9|issue=10|pages=1218–20|pmid=17001340|doi=10.1038/nn1770}}</ref>
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| − | Genetic factors are the most significant cause for autism spectrum disorders. Early studies of twins estimated [[heritability]] to be more than 90%; in other words, that genetics explains more than 90% of autism cases.<ref name=Freitag/> When only one identical twin is autistic, the other often has learning or social disabilities. For adult siblings, the risk of having one or more features of the broader autism phenotype might be as high as 30%,<ref name=Folstein>{{cite journal|author=Folstein SE, Rosen-Sheidley B|title=Genetics of autism: complex aetiology for a heterogeneous disorder|journal=Nat Rev Genet|date=2001|volume=2|issue=12|pages=943–55|doi=10.1038/35103559|pmid=11733747}}</ref> much higher than the risk in controls.<ref>{{cite journal |journal= J Child Psychol Psychiatry |year=1994 |volume=35 |issue=5 |pages=877–900 |title= A case-control family history study of autism |author= Bolton P, Macdonald H, Pickles A ''et al.'' |doi=10.1111/j.1469-7610.1994.tb02300.x |pmid=7962246}}</ref>
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| − | The [[Heritability of autism|genetics of autism]] is complex.<ref name=Freitag/> For each autistic individual, [[mutation]]s in more than one gene may be implicated. Mutations in different sets of genes may be involved in different autistic individuals. There may be significant interactions among mutations in several genes, or between the environment and mutated genes. By identifying genetic markers inherited with autism in family studies, numerous candidate genes have been located, most of which encode proteins involved in [[neural development]] and function.<ref>{{cite journal |author=Persico AM, Bourgeron T |title=Searching for ways out of the autism maze: genetic, epigenetic and environmental clues |journal=Trends Neurosci|volume=29 |issue=7 |pages=349–58 |year=2006 |pmid=16808981 |doi=10.1016/j.tins.2006.05.010}}</ref> However, for most of the candidate genes, the actual mutations that increase the risk for autism have not been identified. Typically, autism cannot be traced to a [[Mendelian]] (single-gene) mutation or to a single [[chromosome abnormality]] such as [[fragile X syndrome]] or [[22q13 deletion syndrome]].<ref name=Cohen/><ref name=Mueller/>
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| − | [[Image:Single Chromosome Mutations.png|thumb|Deletion (1), duplication (2) and inversion (3) are all [[chromosome abnormalities]] that have been implicated in autism.<ref name=Beaudet/>]]
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| − | The large number of autistic individuals with unaffected family members may result from [[copy number variation]]s (CNVs)—spontaneous alterations in the genetic material during [[meiosis]] that [[Deletion (genetics)|delete]] or [[gene duplication|duplicate]] genetic material. Sporadic (non-inherited) cases have been examined to identify candidate [[Locus (genetics)|genetic loci]] involved in autism. Using [[array comparative genomic hybridization]] (array CGH), a technique for detecting CNVs, one study found them in 10% of families with one affected child.<ref>{{cite journal |author=Sebat J, Lakshmi B, Malhotra D ''et al.''|title=Strong association of de novo copy number mutations with autism |journal=Science |volume=316 |issue=5823 |pages=445–49 |year=2007 |pmid=17363630 |doi=10.1126/science.1138659}}</ref> Some of the altered loci had been identified in previous studies of inherited autism; many were unique to the sporadic cases examined in this study. Hence, a substantial fraction of autism may be highly heritable but not inherited: that is, the mutation that causes the autism is not present in the parental genome. The fraction of autism traceable to a genetic cause may grow to 30–40% as the resolution of array CGH improves.<ref name=Beaudet>{{cite journal|author=Beaudet AL|title=Autism: highly heritable but not inherited|journal=Nat Med|date=2007|volume=13|issue=5|pages=534–36|pmid=17479094|doi=10.1038/nm0507-534}}</ref> The Autism Genome Project database contains [[genetic linkage]] and CNV data that connect autism to genetic [[loci]] and suggest that every human [[chromosome]] may be involved.<ref>{{cite journal|journal=Nat Genet|date=2007|volume=39|issue=3|pages=319–28|title=Mapping autism risk loci using genetic linkage and chromosomal rearrangements|author=Autism Genome Project Consortium|doi=10.1038/ng1985|pmid=17322880}}</ref>
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| − | [[Teratogen]]s (agents that cause [[birth defect]]s) related to the risk of autism include exposure of the embryo to [[thalidomide]], [[valproic acid]], or [[misoprostol]], or to [[rubella]] infection in the mother. These cases are rare.<ref name=Szpir>{{cite journal|journal=Environ Health Perspect|date=2006|volume=114|issue=7|pages=A412–18|title=Tracing the origins of autism: a spectrum of new studies|author=Szpir M|url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?pubmedid=16835042|pmid=16835042}}</ref> All known teratogens appear to act during the first eight weeks from [[Human fertilization|conception]], and though this does not exclude the possibility that autism can be initiated or affected later, it is strong evidence that autism arises very early in development.<ref name=Arndt>{{cite journal|journal=Int J Dev Neurosci|date=2005|volume=23|issue=2–3|pages=189–99|title=The teratology of autism|author=Arndt TL, Stodgell CJ, Rodier PM|doi=10.1016/j.ijdevneu.2004.11.001|pmid=15749245}}</ref> Other possible contributors to autism include gastrointestinal or immune system abnormalities, allergies, and the exposure of children to drugs, vaccines, infection, certain foods,<ref name=Christison/> or heavy metals; the evidence for these risk factors is anecdotal and has not been confirmed by reliable studies,<ref name=Rutter/> and extensive further searches are underway.<ref name=Szpir/> Parents may first become aware of autistic symptoms in their child around the time of a routine vaccination. Although there is overwhelming scientific evidence that there is no causal connection between the [[Vaccine controversy#The MMR controversy|measles-mumps-rubella vaccine and autism]], or between the vaccine preservative [[Thiomersal controversy|thiomersal and autism]], parental concern has led to a decreasing uptake of [[childhood immunizations]] and the increasing likelihood of [[Measles#Public health|measles outbreaks]].<ref name=Doja>{{cite journal|journal=Can J Neurol Sci|date=2006|volume=33|issue=4|pages=341–46|title=Immunizations and autism: a review of the literature|author=Doja A, Roberts W|pmid=17168158}}</ref>
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| − | ==Mechanism==
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| − | 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.<ref name=Penn>{{cite journal|author=Penn HE|title=Neurobiological correlates of autism: a review of recent research|journal=Child Neuropsychol|date=2006|volume=12|issue=1|pages=57–79|doi=10.1080/09297040500253546|pmid=16484102}}</ref>
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| − | ===Pathophysiology===
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| − | [[Image:Autismbrain.jpg|thumb|Autism affects many parts of the brain.]]
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| − | Autism appears to result from developmental factors that affect many or all functional brain systems, as opposed to localized physical damage.<ref name=Mueller>{{cite journal|journal=Ment Retard Dev Disabil Res Rev|date=2007|volume=13|issue=1|pages=85–95|title=The study of autism as a distributed disorder|author=Müller RA|doi=10.1002/mrdd.20141|pmid=17326118}}</ref> Many major structures of the [[human brain]] have been implicated. Consistent [[Neuroanatomy|neuroanatomical]] abnormalities have been found in the development of the [[cerebral cortex]]; and in the [[cerebellum]] and related [[inferior olive]], which have a significant decrease in the number of [[Purkinje cell]]s. Brain weight and volume and head circumference tend to be greater in autistic children; the effects of these are unknown.<ref>{{cite journal|journal=J Neurosci|date=2006|volume=26|issue=26|pages=6897–6906|title=The developmental neurobiology of autism spectrum disorder|author=DiCicco-Bloom E, Lord C, Zwaigenbaum L ''et al.''|doi=10.1523/JNEUROSCI.1712-06.2006|pmid=16807320|url=http://www.jneurosci.org/cgi/content/full/26/26/6897}}</ref> It may be due to poorly regulated growth of neurons.<ref name=Penn/>
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| − | Interactions between the [[immune system]] and the nervous system begin early during [[embryogenesis]], and successful neurodevelopment depends on a balanced immune response. Several symptoms consistent with a poorly regulated immune response have been reported in autistic children. It is possible that aberrant immune activity during critical periods of neurodevelopment is part of the mechanism of some forms of ASD.<ref>{{cite journal|journal=J Leukoc Biol|date=2006|volume=80|issue=1|pages=1–15|title=The immune response in autism: a new frontier for autism research|author=Ashwood P, Wills S, Van de Water J|doi=10.1189/jlb.1205707|pmid=16698940|url=http://www.jleukbio.org/cgi/content/full/80/1/1}}</ref> Given the lack of data in this area, it is still hard to draw conclusions about the role of immune factors in autism.<ref>{{cite journal|journal=J Autism Dev Disord|date=2002|volume=32|issue=4|pages=337–45|title=Brief report: immune factors in autism: a critical review|author=Krause I, He XS, Gershwin ME, Shoenfeld Y|doi=10.1023/A:1016391121003|pmid=12199139}}</ref>
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| − | Several [[neurotransmitter]] abnormalities have been detected in autism, notably increased blood levels of [[serotonin]]. Whether these lead to structural or behavioral abnormalities is unclear.<ref name=Penn/>
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| − | The [[Mirror neuron|mirror neuron system]] (MNS) theory of autism hypothesizes that distortion in the development of the MNS interferes with imitation and leads to autism's core features of social impairment and communication difficulties. The MNS operates when an animal performs an action or observes another animal of the same species perform the same action. The MNS may contribute to an individual's understanding of other people by enabling the modeling of their behavior via embodied simulation of their actions, intentions, and emotions.<ref>MNS and autism:
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| − | *{{cite journal|journal=Sci Am|year=2006|volume=295|issue=5|pages=62–69|title=Broken mirrors: a theory of autism|author=[[Vilayanur S. Ramachandran|Ramachandran VS]], Oberman LM|pmid=17076085|url=http://www.sciam.com/article.cfm?articleID=000B7F38-893D-152E-88E283414B7F0000}}
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| − | *{{cite journal|author=Williams JHG, Whiten A, Suddendorf T, Perrett DI|title=Imitation, mirror neurons and autism|journal=Neurosci Biobehav Rev|date=2001|volume=25|issue=4|pages=287–95|doi=10.1016/S0149-7634(01)00014-8|pmid=11445135}}</ref> Several studies have tested this hypothesis by demonstrating structural abnormalities in MNS regions of individuals with ASD, delay in the activation in the core circuit for imitation in individuals with Asperger's, and a correlation between reduced MNS activity and severity of the syndrome in children with ASD.<ref name=Iacoboni>{{cite journal|journal=Nat Rev Neurosci|date=2006|volume=7|issue=12|pages=942–51|title=The mirror neuron system and the consequences of its dysfunction|author=Iacoboni M, Dapretto M|doi=10.1038/nrn2024|pmid=17115076}}</ref>
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| − | [[Image:FMRI.jpg|thumb|[[Functional magnetic resonance imaging]] provides some evidence for the underconnectivity theory of autism.]]
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| − | The underconnectivity theory of autism hypothesizes that autism is marked by underfunctioning high-level neural connections and synchronization, along with an excess of low-level processes.<ref>{{cite journal|journal=Brain|date=2004|volume=127|issue=8|pages=1811–21|title=Cortical activation and synchronization during sentence comprehension in high-functioning autism: evidence of underconnectivity|author=Just MA, Cherkassky VL, Keller TA, Minshew NJ|doi=10.1093/brain/awh199|pmid=15215213|url=http://brain.oxfordjournals.org/cgi/content/full/127/8/1811}}</ref> Evidence for this theory has been found in [[functional neuroimaging]] studies on autistic individuals<ref name=Williams>{{cite journal |author=Williams DL, Goldstein G, Minshew NJ |title=Neuropsychologic functioning in children with autism: further evidence for disordered complex information-processing |journal=Child neuropsychol |volume=12 |issue=4–5 |pages=279–98 |year=2006 |pmid=16911973 |doi=10.1080/09297040600681190 |url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?pubmedid=16911973}}</ref> and by a [[brain wave]] study that suggested that adults with ASD have local overconnectivity in the [[Cerebral cortex|cortex]] and weak functional connections between the [[frontal lobe]] and the rest of the cortex.<ref>{{cite journal|author=Murias M, Webb SJ, Greenson J, Dawson G|title=Resting state cortical connectivity reflected in EEG coherence in individuals with autism|journal=Biol Psychiatry|volume=62|issue=3|pages=270–73 |year=2007|pmid=17336944|doi=10.1016/j.biopsych.2006.11.012}}</ref> Other evidence suggests the underconnectivity is mainly within each [[Cerebral hemisphere|hemisphere]] of the cortex and that autism is a disorder of the [[Cerebral cortex#Association areas|association cortex]].<ref>{{cite journal|journal=Arch Neurol|date=2007|volume=64|issue=7|pages=945–50|title=The new neurobiology of autism: cortex, connectivity, and neuronal organization|author=Minshew NJ, Williams DL|pmid=17620483}}</ref>
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| − | ===Neuropsychology===
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| − | Two major categories of [[cognitive]] theories have been proposed about the links between autistic brains and behavior.
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| − | The first category focuses on deficits in social cognition. Hyper-systemizing hypothesizes that autistic individuals can systematize—that is, they can develop internal rules of operation to handle internal events—but are less effective at [[Empathy|empathizing]] by handling events generated by other agents.<ref name=hypersystem>{{cite journal|author=[[Simon Baron-Cohen|Baron-Cohen S]]|title=The hyper-systemizing, assortative mating theory of autism|journal=Prog Neuropsychopharmacol Biol Psychiatry|date=2006|volume=30|issue=5|pages=865–72|doi=10.1016/j.pnpbp.2006.01.010|pmid=16519981}}</ref> It extends the extreme male brain theory, which hypothesizes that autism is an extreme case of the male brain, defined psychometrically as individuals in whom [[EQ SQ Theory|systemizing is better than empathizing]].<ref>{{cite journal|author=Baron-Cohen S|title=The extreme male brain theory of autism|journal=Trends Cogn Sci|date=2002|volume=6|issue=6|pages=248–54|doi=10.1016/S1364-6613(02)01904-6|pmid=12039606}}</ref> This in turn is related to the earlier [[theory of mind]], which hypothesizes that autistic behavior arises from an inability to ascribe mental states to oneself and others. The theory of mind is supported by autistic children's atypical responses to the [[Sally-Anne test]] for reasoning about others' motivations,<ref>{{cite journal |author=Baron-Cohen S, Leslie AM, Frith U|title=Does the autistic child have a 'theory of mind'? |journal=Cognition |volume=21 |issue=1 |pages=37–46 |year=1985 |doi=10.1016/0010-0277(85)90022-8 |pmid=2934210 |url=http://ruccs.rutgers.edu/~aleslie/Baron-Cohen%20Leslie%20&%20Frith%201985.pdf |format = PDF | accessdate=2007-06-28}}</ref> and is mapped well from the mirror neuron system theory of autism.<ref name=Iacoboni/>
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| − | The second category focuses on nonsocial or general processing. [[Executive dysfunction]] hypothesizes that autistic behavior results in part from deficits in flexibility, planning, and other forms of [[executive function]]. A strength of the theory is predicting stereotyped behavior and narrow interests;<ref>{{cite journal|author=Hill EL|title=Executive dysfunction in autism|journal=Trends Cogn Sci|year=2004|volume=8|issue=1|pages=26–32|doi=10.1016/j.dr.2004.01.001|pmid=14697400}}</ref> a weakness is that executive function deficits are not found in young autistic children.<ref name=Sigman/> [[Weak central coherence theory]] hypothesizes that a limited ability to see the big picture underlies the central disturbance in autism. One strength of this theory is predicting special talents and peaks in performance in autistic people.<ref>{{cite journal|author=Happé F, [[Uta Frith|Frith U]]|title=The weak coherence account: detail-focused cognitive style in autism spectrum disorders|journal=J Autism Dev Disord|date=2006|volume=36|issue=1|pages=5–25|doi=10.1007/s10803-005-0039-0|pmid=16450045}}</ref> A related theory—enhanced perceptual functioning—focuses more on the superiority of locally oriented and [[perceptual]] operations in autistic individuals.<ref>{{cite journal|journal=J Autism Dev Disord|date=2006|volume=36|issue=1|pages=27–43|title=Enhanced perceptual functioning in autism: an update, and eight principles of autistic perception|author=Mottron L, [[Michelle Dawson|Dawson M]], Soulières I, Hubert B, Burack J|doi=10.1007/s10803-005-0040-7|pmid=16453071}}</ref> The latter two theories map well from the underconnectivity theory of autism.
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| − | Neither category is satisfactory on its own; social cognition theories poorly address autism's rigid and repetitive behaviors, while the nonsocial theories have difficulty explaining social impairment and communication difficulties.<ref name=HappeTime/> A combined theory based on multiple deficits may prove to be more useful.<ref name=Rajendran>{{cite journal |journal=Dev Rev |year=2007 |volume=27 |issue=2 |pages=224–60 |title= Cognitive theories of autism |author= Rajendran G, Mitchell P |doi=10.1016/j.dr.2007.02.001}}</ref>
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| − | | |
| − | ==Screening==
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| − | Parents are usually the first to notice unusual behaviors in their child.<ref name=Strock>{{cite paper|author=Strock, M|date=2007|title=Autism spectrum disorders (pervasive developmental disorders)|version=NIH-04-5511|publisher=National Institute of Mental Health|url=http://www.nimh.nih.gov/publicat/autism.cfm|accessdate=2007-06-27}}</ref> As postponing treatment may affect long-term outcome, any of the following signs is reason to have a child evaluated by a specialist without delay:
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| − | *No [[babbling]] by 12 months.
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| − | *No [[Gesture|gesturing]] (pointing, waving goodbye, etc.) by 12 months.
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| − | *No single words by 16 months.
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| − | *No two-word spontaneous phrases (not including [[echolalia]]) by 24 months.
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| − | *Any loss of any language or social skills, at any age.<ref name=Filipek/>
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| − | The [[American Academy of Pediatrics]] recommends that all children be [[Screening (medicine)|screened]] for ASD at the 9-, 18-, and 30-month well-child doctor visits, using autism-specific formal screening tests.<ref>{{cite journal|journal=Pediatrics|date=2006|volume=118|issue=1|pages=405–20|title=Identifying infants and young children with developmental disorders in the medical home: an algorithm for developmental surveillance and screening|author=Council on Children With Disabilities, Section on Developmental Behavioral Pediatrics, Bright Futures Steering Committee, Medical Home Initiatives for Children With Special Needs Project Advisory Committee|doi=10.1542/peds.2006-1231|url=http://pediatrics.aappublications.org/cgi/content/full/118/1/405}} {{cite journal|journal=Pediatrics|date=2006|volume=118|issue=4|pages=1808–09|doi=10.1542/peds.2006-2405|title=Errata|author=<nowiki>[Same authors]</nowiki>|pmid=16818591|url=http://pediatrics.aappublications.org/cgi/content/full/118/4/1808}}</ref> In contrast, the UK National Screening Committee recommends against screening for ASD in the general population, because screening tools have not been fully validated and interventions lack sufficient evidence for effectiveness.<ref>{{cite journal|journal=Autism|date=2006|volume=10|issue=1|pages=11–35|title=Screening for autism spectrum disorders: what is the evidence?|author=Williams J, Brayne C|doi=10.1177/1362361306057876|pmid=16522708}}</ref>
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| − | Genetic screening for autism is generally still impractical. As 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.<ref>{{cite journal|journal=Am J Med Genet C Semin Med Genet|date=2006|volume=142C|issue=1|pages=52–57|title=Genetic counseling and ethical issues for autism|author=McMahon WM, Baty BJ, Botkin J|doi=10.1002/ajmg.c.30082|pmid=16419100}}</ref>
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| − | ==Diagnosis==
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| − | 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]].<ref>{{cite book|title=Diagnostic and Statistical Manual of Mental Disorders|edition=4th ed., text revision ([[DSM-IV-TR]])|author=[[American Psychiatric Association]]|date=2000|isbn=0890420254|chapter=Diagnostic criteria for 299.00 Autistic Disorder|chapterurl=http://www.behavenet.com/capsules/disorders/autistic.htm|accessdate=2007-06-25}}</ref> [[ICD-10]] uses essentially the same definition.<ref name=ICD-10-F84.0>{{cite book|chapterurl=http://www.who.int/classifications/apps/icd/icd10online/?gf80.htm+f840|date=2006|accessdate=2007-06-25|title=International Statistical Classification of Diseases and Related Health Problems|edition=10th ed. (ICD-10)|author=[[World Health Organization]]|chapter=F84. Pervasive developmental disorders}}</ref>
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| − | 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.<ref name=Volkmar/>
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| − | 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 disorder]]<ref name=Dover/> such as [[Landau-Kleffner syndrome]].<ref>{{cite journal |journal= Dev Med Child Neurol |year=2000 |volume=42 |issue=5 |pages=349–53 |title= Autistic regression and Landau-Kleffner syndrome: progress or confusion? |author= Mantovani JF |doi=10.1111/j.1469-8749.2000.tb00104.x |pmid=10855658}}</ref> 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.<ref name=Dover>{{cite journal|journal=Arch Dis Child|date=2007|volume=92|issue=6|pages=540–45|title=How to diagnose autism|author=Dover CJ, Le Couteur A|doi=10.1136/adc.2005.086280|pmid=17515625}}</ref> ASD can sometimes be diagnosed by age 14 months,<ref>{{cite journal|journal=Arch Gen Psychiatry|date=2007|volume=64|issue=7|pages=853–64|title=Social and communication development in toddlers with early and later diagnosis of autism spectrum disorders|author=Landa RJ, Holman KC, Garrett-Mayer E|pmid=17606819}}</ref> but 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.<ref>{{cite journal|journal=J Dev Behav Pediatr|date=2006|volume=27|issue=2 Suppl|pages=S79–87|title=Examination of the time between first evaluation and first autism spectrum diagnosis in a population-based sample|author=Wiggins LD, Baio J, Rice C|pmid=16685189}}</ref>
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| − | Underdiagnosis and overdiagnosis are problems in marginal cases, and much of the recent increase in the number of reported ASD cases is likely due to changes in diagnostic practices. The increasing popularity of drug treatment options and the expansion of benefits has given providers incentives to diagnose ASD, resulting in some overdiagnosis of children with uncertain symptoms. Conversely, the cost of screening and diagnosis and the challenge of obtaining payment can inhibit or delay diagnosis.<ref>{{cite journal|author=Shattuck PT, Grosse SD|title=Issues related to the diagnosis and treatment of autism spectrum disorders|journal=Ment Retard Dev Disabil Res Rev|date=2007|volume=13|issue=2|pages=129–35|doi=10.1002/mrdd.20143|pmid=17563895}}</ref> It is particularly hard to diagnose autism among the [[visually impaired]], partly because some of its diagnostic criteria depend on vision, and partly because autistic symptoms overlap with those of common blindness syndromes.<ref>{{cite journal|title=Visual impairment and autism: current questions and future research|author=Cass H|journal=Autism|date=1998|volume=2|issue=2|pages=117–38|doi=10.1177/1362361398022002}}</ref>
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| − | The symptoms of autism and ASD begin early in childhood but are occasionally missed. Adults may seek retrospective diagnoses to help them or their friends and family understand themselves, to help their employers make adjustments, or in some locations to claim disability living allowances or other benefits.<ref>{{cite web|publisher=The National Autistic Society|title=Why get a diagnosis as an adult?|date=2005|url=http://www.nas.org.uk/nas/jsp/polopoly.jsp?a=8018|accessdate=2007-06-29}}</ref>
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| − | ==Treatment==
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| − | {{main|Autism therapies}}
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| − | The goal of treatment is to manage and improve symptoms and functioning. 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.<ref>{{cite journal|journal=Can J Psychiatry|date=2003|volume=48|issue=8|pages=506–16|title=Autism spectrum disorders: early detection, intervention, education, and psychopharmacological management|author=Bryson SE, Rogers SJ, Fombonne E|pmid=14574826|url=http://ww1.cpa-apc.org:8080/Publications/Archives/CJP/2003/september/bryson.asp}}</ref><ref name=SG/> Among the available approaches, [[applied behavior analysis]] (ABA) has demonstrated [[efficacy]] in promoting social and language development and in reducing behaviors that interfere with learning and cognitive functioning;<ref name=SG/> ABA focuses on teaching tasks one-on-one using the [[behaviorist]] principles of stimulus, response and reward.<ref name=Howard/> Cognitive therapies based on comprehensive programs in treatment centers are a common alternative: for example, [[Treatment and education of autistic and related communication handicapped children|TEACCH]] focuses on structuring the physical environment and using visual supports for language development tasks.<ref name=SG>{{cite book|title=Mental Health: A Report of the Surgeon General|author=U.S. Dept. of Health and Human Services|location=Rockville, MD|publisher=U.S. Department of Health and Human Services, Substance Abuse and Mental Health Services Administration, Center for Mental Health Services, National Institutes of Health, National Institute of Mental Health|date=1999|chapter=Autism|chapterurl=http://www.surgeongeneral.gov/library/mentalhealth/chapter3/sec6.html#autism}} Retrieved on 2007-07-11.</ref> A 2005 California study found that early intensive behavior analytic treatment, a form of ABA, was substantially more effective for preschool children with autism than the mixture of methods provided in many programs.<ref name=Howard>{{cite journal |author=Howard JS, Sparkman CR, Cohen HG, Green G, Stanislaw H |title=A comparison of intensive behavior analytic and eclectic treatments for young children with autism |journal=Res Dev Disabil |volume=26 |issue=4 |pages=359–83 |year=2005 |pmid=15766629 |doi=10.1016/j.ridd.2004.09.005}}</ref> The limited research on the effectiveness of adult residential programs shows mixed results.<ref>{{cite journal|journal=J Autism Dev Disord|date=2003|volume=33|issue=2|pages=131–40|title=Effects of a model treatment approach on adults with autism|author=Van Bourgondien ME, Reichle NC, Schopler E|doi=10.1023/A:1022931224934|pmid=12757352}}</ref>
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| − | Medications are often used to treat problems associated with ASD. More than half of U.S. children diagnosed with ASD are prescribed [[psychoactive drug]]s or [[anticonvulsant]]s, with the most common drug classes being [[antidepressant]]s, [[stimulant]]s, and [[antipsychotic]]s.<ref>{{cite journal|journal=J Child Adolesc Psychopharmacol|date=2007|volume=17|issue=3|pages=348–55|title=Medication use among children with autism spectrum disorders|author=Oswald DP, Sonenklar NA|doi=10.1089/cap.2006.17303|pmid=17630868}}</ref> In the United States, the antipsychotic [[risperidone]] is approved for treating symptomatic irritability in autistic children and adolescents.<ref>{{cite press release|publisher=FDA|date=2006-10-06|url=http://www.fda.gov/bbs/topics/NEWS/2006/NEW01485.html|accessdate=2007-08-08|title=FDA approves the first drug to treat irritability associated with autism, Risperdal}}</ref> Other drugs are prescribed [[off-label]], which means they have not been approved for treating ASD. For example, [[serotonin reuptake inhibitors]] and [[dopamine]] blockers can sometimes reduce some symptoms.<ref name=Penn/> However, there is scant reliable research about the effectiveness or safety of drug treatments for adolescents and adults with ASD.<ref>{{cite journal|journal=Autism|date=2007|volume=11|issue=4|pages=335–48|title=Systematic review of the effectiveness of pharmacological treatments for adolescents and adults with autism spectrum disorder|author=Broadstock M, Doughty C, Eggleston M|doi=10.1177/1362361307078132|pmid=17656398}}</ref> A person with ASD may respond atypically to medications, the medications can have adverse side effects, and no known medication relieves autism's core symptoms of social and communication impairments.<ref name=Strock/>
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| − | Many other therapies and interventions are available. Few are supported by scientific studies.<ref name=Francis>{{cite journal|journal=Dev Med Child Neurol|date=2005|volume=47|issue=7|pages=493–99|title=Autism interventions: a critical update|author=Francis K|pmid=15991872|url=http://journals.cambridge.org/production/action/cjoGetFulltext?fulltextid=313204|format=PDF}}</ref><ref name=Sigman/><ref>Lack of support for interventions:
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| − | *{{cite journal|author=Herbert JD, Sharp IR, Gaudiano BA|title=Separating fact from fiction in the etiology and treatment of autism: a scientific review of the evidence|journal=Sci Rev Ment Health Pract|volume=1|issue=1|pages=23–43|year=2002|url=http://www.srmhp.org/0101/autism.html}}
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| − | *{{cite book|title=Neurodevelopmental Disorders|editor=Fleischhacker WW, Brooks DJ|chapter=The effectiveness of interventions for children with autism|doi=10.1007/3-211-31222-6_6|author=Howlin P|date=2005|pages=101–119|publisher=Springer|isbn=3211262911}}PMID 16355605.
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| − | *{{cite journal|journal=J Autism Dev Disord|date=2007|title=Social skills interventions for children with Asperger's syndrome or high-functioning autism: a review and recommendations|author=Rao PA, Beidel DC, Murray MJ|doi=10.1007/s10803-007-0402-4|pmid=17641962}}</ref><ref name=Aman/> Treatment approaches lack empirical support in [[quality of life|quality-of-life]] contexts, and many programs focus on success measures that lack predictive validity and real-world relevance.<ref name=Burgess/> Scientific evidence appears to matter less to service providers than program marketing, training availability, and parent requests.<ref>{{cite journal|url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?pubmedid=16467905|journal=Focus Autism Other Dev Disabl|date=2005|volume=20|issue=2|pages=66–79|title=Early intervention practices for children with autism: descriptions from community providers|author=Stahmer AC, Collings NM, Palinkas LA|pmid=16467905}}</ref> Even if they do not help, conservative treatments such as changes in diet are probably harmless aside from their bother and cost.<ref name=Christison>{{cite journal|journal=J Dev Behav Pediatr|date=2006|volume=27|issue=2 Suppl 2|pages=S162–71|title=Elimination diets in autism spectrum disorders: any wheat amidst the chaff?|author=Christison GW, Ivany K|pmid=16685183}}</ref> Dubious invasive treatments are a much more serious matter: for example, in 2005, botched [[chelation therapy]] killed a 5-year-old autistic boy.<ref name=Doja/>
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| − | Treatment is expensive;<ref>{{cite journal |journal= J Autism Dev Disord |year=2007 |title= Medical expenditures for children with an autism spectrum disorder in a privately insured population |author= Shimabukuro TT, Grosse SD, Rice C |doi=10.1007/s10803-007-0424-y |pmid=17690969}}</ref> indirect costs are more so. A U.S. study estimated the average additional lifetime cost due exclusively to autism to be $3.2 million in 2003 U.S. dollars for an autistic individual born in 2000, with about 10% medical care, 30% nonmedical care such as child care and education, and 60% the lost economic productivity of individuals and their parents.<ref>{{cite journal|journal=Arch Pediatr Adolesc Med|date=2007|volume=161|issue=4|pages=343–49|title=The lifetime distribution of the incremental societal costs of autism|author=Ganz ML|pmid=17404130|url=http://archpedi.ama-assn.org/cgi/content/full/161/4/343}}</ref> A British study estimated an average lifetime cost of ₤2.4 million in 1997–1998 British pounds.<ref>{{cite journal|journal=Autism|date=2001|volume=5|issue=1|pages=7–22|title=The economic impact of autism in Britain|author=Järbrink K, Knapp M|doi=10.1177/1362361301005001002|pmid=11708392}}</ref> Legal rights to treatment are complex, vary with location and age, and require advocacy by caregivers.<ref name=Aman>{{cite journal|journal=J Clin Psychiatry|date=2005|volume=66|issue=Suppl 10|pages=38–45|title=Treatment planning for patients with autism spectrum disorders|author=Aman MG|pmid=16401149}}</ref> 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.<ref>{{cite journal|journal=J Fam Econ Iss|date=2007|volume=28|issue=2|pages=247–64|doi=10.1007/s10834-007-9059-6|title=Financial issues associated with having a child with autism|author=Sharpe DL, Baker DL}}</ref> After childhood, key treatment issues include residential care, job training and placement, sexuality, social skills, and estate planning.<ref name=Aman/>
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| − | ==Prognosis==
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| − | No cure is known for autism. Most children with autism lack social support, meaningful relationships, future employment opportunities or [[Self-determination theory|self-determination]].<ref name=Burgess>{{cite journal|author=Burgess AF, Gutstein SE|date=2007|title=Quality of life for people with autism: raising the standard for evaluating successful outcomes|journal=Child Adolesc Ment Health|volume=12|issue=2|pages=80–86|doi=10.1111/j.1475-3588.2006.00432.x}}</ref> Although core difficulties remain, the severity of symptoms often becomes less marked in later childhood.<ref>{{cite journal|author=Howlin P|title=Autism spectrum disorders|journal=Psychiatry|volume=5|issue=9|date=2006|pages=320–24|doi=10.1053/j.mppsy.2006.06.007}}</ref> Few high-quality studies address long-term [[prognosis]]. Some adults show modest improvement in some symptoms, but some decline; no study has focused on autism after midlife.<ref>{{cite journal|journal=Ment Retard Dev Disabil Res Rev|volume=10|issue=4|pages=234–47|date=2004|title=Trajectory of development in adolescents and adults with autism|author=Seltzer MM, Shattuck P, Abbeduto L, Greenberg JS|doi=10.1002/mrdd.20038|pmid=15666341}}</ref> Acquiring language before age 6, having [[IQ]] above 50, and having a marketable skill all predict better outcomes; independent living is unlikely with severe autism.<ref>{{cite journal|author=Tidmarsh L, Volkmar FR|title=Diagnosis and epidemiology of autism spectrum disorders|journal=Can J Psychiatry|volume=48|issue=8|pages=517–25|date=2003|pmid=14574827|url=http://ww1.cpa-apc.org:8080/Publications/Archives/CJP/2003/september/tidmarsh.asp}}</ref> A 2004 British study of 68 adults who were diagnosed before 1980 as autistic children with IQ above 50 found that 12% achieved a high level of independence as adults, 10% had some friends and were generally in work but required some support, 19% had some independence but were generally living at home and needed considerable support and supervision in daily living, 46% needed specialist residential provision from facilities specializing in ASD with a high level of support and very limited autonomy, and 12% needed high-level hospital care.<ref name=Howlin>{{cite journal|author=Howlin P, Goode S, Hutton J, Rutter M|title=Adult outcome for children with autism|journal=J Child Psychol Psychiatry|date=2004|volume=45|issue=2|pages=212–29|pmid=14982237|doi=10.1111/j.1469-7610.2004.00215.x}}</ref> Changes in diagnostic practice and increased availability of effective early intervention make it unclear whether these findings can be generalized to recently diagnosed children.<ref name=Newschaffer/>
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| − | ==Epidemiology==
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| − | Estimates of the [[prevalence]] of autism vary widely depending on diagnostic criteria, age of children screened, and geographical location.<ref>{{cite journal|author=Williams JG, Higgins JPT, Brayne CEG|title=Systematic review of prevalence studies of autism spectrum disorders|journal=Arch Dis Child|date=2006|volume=91|issue=1|pages=8–15|pmid=15863467|doi=10.1136/adc.2004.062083|url=http://adc.bmj.com/cgi/content/full/91/1/8}}</ref> Most recent [[review]]s tend to estimate a prevalence of 1–2 per 1,000 for autism and close to 6 per 1,000 for ASD;<ref name=Newschaffer>{{cite journal|author=Newschaffer CJ, Croen LA, Daniels J ''et al.''|title=The epidemiology of autism spectrum disorders|journal=Annu Rev Public Health|year=2007|volume=28|pages=235–58|pmid=17367287|doi=10.1146/annurev.publhealth.28.021406.144007}}</ref> [[PDD-NOS]] is the vast majority of ASD, [[Asperger's]] is about 0.3 per 1,000 and the atypical forms [[childhood disintegrative disorder]] and [[Rett syndrome]] are much rarer.<ref>{{cite journal|journal=J Clin Psychiatry|date=2005|volume=66|issue=Suppl 10|pages=3–8|title=Epidemiology of autistic disorder and other pervasive developmental disorders|author=[[Eric Fombonne|Fombonne E]]|pmid=16401144}}</ref> A 2006 study of nearly 57,000 British nine- and ten-year-olds reported a prevalence of 3.89 per 1,000 for autism and 11.61 per 1,000 for ASD; these higher figures could be associated with broadening diagnostic criteria.<ref name=Baird>{{cite journal|title=Prevalence of disorders of the autism spectrum in a population cohort of children in South Thames: the Special Needs and Autism Project (SNAP)|author=Baird G, Simonoff E, Pickles A ''et al.''|journal=Lancet|volume=368|issue=9531|pages=210–15|date=2006|pmid=16844490|doi=10.1016/S0140-6736(06)69041-7}}</ref>
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| − | The risk of autism is associated with several [[prenatal]] and [[perinatal]] risk factors. A 2007 review of [[risk factors]] found associated parental characteristics that included advanced maternal age, advanced paternal age, and maternal place of birth outside Europe or North America, and also found associated [[obstetric]] conditions that included [[low birth weight]] and [[gestation]] duration, and [[Hypoxia (medical)|hypoxia]] during [[childbirth]].<ref>{{cite journal|author=Kolevzon A, Gross R, Reichenberg A|title=Prenatal and perinatal risk factors for autism|journal=Arch Pediatr Adolesc Med|volume=161|issue=4|date=2007|pages=326–33|pmid=17404128}}</ref>
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| − | About 10–15% of autism cases have an identifiable [[Mendelian]] (single-gene) condition, [[chromosome abnormality]], or other genetic syndrome,<ref name=Folstein/> and ASD is associated with several [[genetic disorder]]s.<ref>{{cite journal|journal=Brain Dev|date=2007|volume=29|issue=5|pages=257–72|title=Childhood autism and associated comorbidities|author=Zafeiriou DI, Ververi A, Vargiami E|doi=10.1016/j.braindev.2006.09.003|pmid=17084999}}</ref> Autism is associated with [[mental retardation]]: a 2001 British study of 26 autistic children found about 30% with intelligence in the normal range ([[IQ]] above 70), 50% with mild to moderate retardation, and about 20% with severe to profound retardation (IQ below 35). For ASD other than autism the association is much weaker: the same study reported about 94% of 65 children with PDD-NOS or Asperger's had normal intelligence.<ref>{{cite journal|author=Chakrabarti S, Fombonne E|title=Pervasive developmental disorders in preschool children|journal=JAMA|date=2001|volume=285|issue=24|pages=3093–99|pmid=11427137|url=http://jama.ama-assn.org/cgi/content/full/285/24/3093}}</ref> ASD is also associated with [[epilepsy]], with variations in risk of epilepsy due to age, cognitive level, and type of language disorder.<ref>{{cite journal|author=Tuchman R, Rapin I|title=Epilepsy in autism|journal=Lancet Neurol|date=2002|volume=1|issue=6|pages=352–58|doi=10.1016/S1474-4422(02)00160-6|pmid=12849396}}</ref> Boys are at higher risk for autism than girls. The ASD sex ratio averages 4.3:1 and is greatly modified by cognitive impairment: it may be close to 2:1 with mental retardation and more than 5.5:1 without. Recent studies have found no association with socioeconomic status, and have reported inconsistent results about associations with race or ethnicity.<ref name=Newschaffer/> [[Phobia]]s, [[Clinical depression|depression]] and other [[Psychopathology|psychopathological]] disorders have often been described along with ASD but this has not been assessed systematically.<ref>{{cite journal|journal=Res Dev Disabil|date=2007|volume=28|issue=4|pages=341–52|title=Comorbid psychopathology with autism spectrum disorder in children: an overview|author=Matson JL, Nebel-Schwalm MS|doi=10.1016/j.ridd.2005.12.004|pmid=16765022}}</ref>
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| − | [[Autism (incidence)|Autism's incidence]], despite its advantages for assessing risk, is less useful in autism epidemiology, as the disorder starts long before it is diagnosed, and the gap between initiation and diagnosis is influenced by many factors unrelated to risk. Attention is focused mostly on whether prevalence is increasing with time. Earlier prevalence estimates were lower, centering at about 0.5 per 1,000 for autism during the 1960s and 1970s and about 1 per 1,000 in the 1980s, as opposed to today's 1–2 per 1,000.<ref name=Newschaffer/>
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| − | [[Image:US-autism-6-11-1996-2005.png|thumb|Reports of autism cases grew dramatically in the U.S. in 1996–2005. It is unknown how much, if any, growth came from changes in autism's [[prevalence]].]]
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| − | The number of reported cases of autism increased dramatically in the 1990s and early 2000s. This increase is largely attributable to changes in diagnostic practices, referral patterns, availability of services, age at diagnosis, and public awareness,<ref>Changes in diagnostic practices:
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| − | *{{cite journal|author=Fombonne E|title=The prevalence of autism|journal=JAMA|date=2003|volume=289|issue=1|pages=87–89|pmid=12503982}}
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| − | *{{cite journal|author=Wing L, Potter D|title=The epidemiology of autistic spectrum disorders: is the prevalence rising?|journal=Ment Retard Dev Disabil Res Rev|volume=8|issue=3|year=2002|pages=151–61|pmid=12216059|doi=10.1002/mrdd.10029}}</ref> though as-yet-unidentified contributing environmental risk factors cannot be ruled out.<ref name=Rutter>{{cite journal|author=[[Michael Rutter|Rutter M]]|title=Incidence of autism spectrum disorders: changes over time and their meaning|journal=Acta Paediatr|volume=94|issue=1|date=2005|pages=2–15|pmid=15858952}}</ref> A widely cited 2002 pilot study concluded that the observed increase in autism in California cannot be explained by changes in diagnostic criteria,<ref>{{cite paper|author=Byrd RS, Sage AC, Keyzer J ''et al.''|publisher=[[M.I.N.D. Institute]]|title=Report to the legislature on the principal findings of the epidemiology of autism in California: a comprehensive pilot study|date=2002|url=http://www.ucdmc.ucdavis.edu/mindinstitute/newsroom/study_final.pdf|accessdate=2006-09-18|format=PDF}}</ref> but a 2006 analysis found that special education data poorly measured prevalence because so many cases were undiagnosed, and that the 1994–2003 U.S. increase was associated with declines in other diagnostic categories, indicating that diagnostic substitution had occurred.<ref>{{cite journal|journal=Pediatrics|date=2006|volume=117|issue=4|pages=1028–37|title=The contribution of diagnostic substitution to the growing administrative prevalence of autism in US special education|author=Shattuck PT|doi=10.1542/peds.2005-1516|pmid=16585296|url=http://pediatrics.aappublications.org/cgi/content/full/117/4/1028}}</ref> It is unknown whether autism's prevalence increased during the same period. An increase in prevalence would suggest directing more attention and funding toward changing environmental factors instead of continuing to focus on genetics.<ref name=Szpir/>
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| − | ==History==
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| − | A few examples of autistic symptoms and treatments were described long before autism was named. The ''[[Table Talk]]'' of [[Martin Luther]] contains a story of a 12-year-old boy who may have been severely autistic.<ref>{{cite journal|journal=Autism|volume=1|issue=1|pages=13–23|date=1997|doi=10.1177/1362361397011004|title=The history of ideas on autism: legends, myths and reality|author=[[Lorna Wing|Wing L]]}}</ref> According to Luther's notetaker [[Johannes Mathesius|Mathesius]], Luther thought the boy was a soulless mass of flesh [[demonic possession|possessed by the devil]], and suggested that he be suffocated.<ref>{{cite web|author=Miles M|date=2005|title=Martin Luther and childhood disability in 16th century Germany: what did he write? what did he say?|publisher=Independent Living Institute|url=http://www.independentliving.org/docs7/miles2005b.html|accessdate=2007-07-18}}</ref> [[Victor of Aveyron]], a [[feral child]] caught in 1798, showed several signs of autism; the medical student [[Jean Itard]] treated him with a behavioral program designed to help him form social attachments and to induce speech via imitation.<ref name=Wolff>{{cite journal|journal=Eur Child Adolesc Psychiatry|date=2004|volume=13|issue=4|pages=201–08|title=The history of autism|author=Wolff S|doi=10.1007/s00787-004-0363-5|pmid=15365889}}</ref>
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| − | The [[New Latin]] word ''autismus'' (English translation ''autism'') was coined by the [[Swiss]] psychiatrist [[Eugen Bleuler]] in 1910 as he was defining symptoms of [[schizophrenia]]. He derived it from the [[Greek language|Greek]] word ''autos'' (αὐτός, meaning ''self''), and used it to mean morbid self-admiration, referring to "autistic withdrawal of the patient to his fantasies, against which any influence from outside becomes an intolerable disturbance."<ref>{{cite journal|author=Kuhn R; tr. Cahn CH|title=Eugen Bleuler's concepts of psychopathology|journal=Hist Psychiatry|volume=15|issue=3|date=2004|pages=361–66|doi=10.1177/0957154X04044603|pmid=15386868}} The quote is a translation of Bleuler's 1910 original.</ref>
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| − | The word ''autism'' took its modern sense in 1943 when [[Leo Kanner]] of the [[Johns Hopkins Hospital]] reported 11 children with striking behavioral similarities and introduced the label ''early infantile autism''.<ref name=Kanner1943>{{cite journal|author=Kanner L|title=Autistic disturbances of affective contact|journal=Nerv Child|volume=2|pages=217–50|date=1943}}</ref> He suggested ''autism'' to describe the children's lack of interest in other people. Almost all the characteristics described in Kanner's first paper on the subject, notably "autistic aloneness" and "insistence on sameness," are still regarded as typical of the autistic spectrum of disorders.<ref name=HappeTime/> About the same time, the [[Vienna|Viennese]] pediatrician [[Hans Asperger]] described a similar form of ASD now known as [[Asperger's]], though for various reasons it was not widely recognized as a separate syndrome until 1981.<ref name=Wolff/>
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| − | Kanner's reuse of ''autism'' led to decades of confused terminology like "infantile schizophrenia," and child psychiatry's focus on maternal deprivation during the mid-1900s led to misconceptions of autism as an infant's response to "[[refrigerator mother]]s." Starting in the late 1960s autism was established as a separate syndrome by demonstrating that it is lifelong, distinguishing it from mental retardation and schizophrenia and from other developmental disorders, and demonstrating the benefits of involving parents in active programs of therapy.<ref>{{cite journal|journal=Can J Psychiatry|date=2003|volume=48|issue=8|pages=503–05|title=Modern views of autism|author=Fombonne E|pmid=14574825|url=http://ww1.cpa-apc.org:8080/Publications/Archives/CJP/2003/september/guesteditorial.asp}}</ref> Since then, the rise of parent organizations and the [[Social stigma|destigmatization]] of childhood ASD have deeply affected how we view ASD, its boundaries, and its treatments.<ref name=Wolff/> The [[Internet]] has helped autistic individuals bypass nonverbal cues and emotional sharing that they find so hard to deal with, and has given them a way to form online communities and work remotely.<ref>{{cite news|author=Biever C|title=Web removes social barriers for those with autism|work=New Scientist|issue=2610|date=2007-06-27|url=http://www.newscientisttech.com/channel/tech/mg19426106.100-web-removes-social-barriers-for-those-with-autism.html|accessdate=2007-06-28}}</ref> [[Sociological and cultural aspects of autism]] have developed: some in the community seek a cure, while others believe that autism is simply another way of being.<ref name=Rajendran/><ref name=Gal>{{cite news|author=Gal L|title=Who says autism's a disease?|work=Haaretz|date=2007-06-28|url=http://www.haaretz.com/hasen/spages/876283.html|accessdate=2007-07-16}}</ref>
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| − | ==References==
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| − | {{reflist|2}}
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| − | ==External links==
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| − | * {{dmoz|Health/Mental_Health/Disorders/Neurodevelopmental/Autism_Spectrum}}
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| − | * [http://www.autism-help.org/ Autism-help.org]
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| − | * [http://www.nichcy.org/resources/autism.asp National Dissemination Center for Children with Disabilities (NICHCY),] autism resources
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| − | {{Credits|Autism|155422430|}}
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