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'''For patient information click [[Autism (patient information)|here]]'''
__NOTOC__
 
'''For patient information, click [[Autism (patient information)|here]]'''
{{Infobox_Disease
{{Infobox_Disease
  | Name = Autism
  | Name = Autism
  | Image = Autism-stacking-cans 2nd edit.jpg
  | Image = Autism-stacking-cans 2nd edit.jpg
  | Caption = Repetitively stacking or lining up objects may indicate autism.<ref name=Johnson/>
  | Caption = Repetitively stacking or lining up objects may indicate autism.
| DiseasesDB = 1142
| ICD10 = {{ICD10|F|84|0|f|80}}
| ICD9 = {{ICD9|299.0}}
| ICDO =
| OMIM = 209850
| MedlinePlus = 001526
| MeshID = D001321
}}
}}
{{SI}}
{{Autism}}
{{CMG}}
{{CMG}} {{AE}} {{ADG}} ; {{HK}} ; {{IQ}} ; {{Akshun}} ; {{CK}} {{SSH}}
 
==Overview==
'''Autism''' is a [[Neurodevelopmental disorders|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]].<ref name=ICD-10-F84.0/>
 
Autism has a strong genetic basis, although the [[Heritability of autism|genetics of autism]] are complex and it is unclear whether ASD is explained more by multigene interactions or by rare [[mutation]]s.<ref name=Abrahams/> 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 childhood [[vaccine]]s, are [[Controversies in autism|controversial]] and the vaccine hypotheses lack convincing 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 actual prevalence has increased is unresolved.<ref name=Newschaffer/>
 
Autism affects many parts of the [[Human brain|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.<ref name=CCD/> Few children with autism live independently after reaching adulthood, but some become successful,<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/>
 
==Classification==
Autism is a brain development disorder that first gives 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), 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/>
 
[[Image:Asperger kl2.jpg|thumb|[[Hans Asperger]] introduced the modern sense of the word ''autism'' in 1938.<ref name=Lyons/>]]
Of the other four PDD forms, [[Asperger syndrome]] is closest to autism in signs and likely causes; [[Rett syndrome]] and [[childhood disintegrative disorder]] share several signs with autism, but may have unrelated causes; [[PDD not otherwise specified]] (PDD-NOS) is diagnosed when the criteria are not met for a more specific disorder.<ref>{{cite journal |author= Lord C, Cook EH, Leventhal BL, 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}}</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://behavenet.com/capsules/disorders/asperger.htm}}</ref> The terminology of autism can be bewildering, with autism, Asperger's and PDD-NOS often called the ''autism spectrum disorders'' (ASD)<ref name=CCD/> or sometimes 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}}</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'' or ''the autisms'' to refer to ASD,<ref>{{cite journal |journal= Curr Opin Neurobiol |date=2007 |volume=17 |issue=1 |pages=103–11 |title= Autism spectrum disorders: developmental disconnection syndromes |author= Geschwind DH, Levitt P |doi=10.1016/j.conb.2007.01.009 |pmid=17275283}}</ref> or equate ASD with PDD.<ref name=Strock/> 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>
 
The manifestations of autism cover a wide [[Spectrum disorder|spectrum]], ranging from individuals with severe impairments—who may be silent, [[mentally disabled]], and locked into hand flapping and rocking—to less impaired individuals who may have active but distinctly odd social approaches, narrowly focused interests, and verbose, pedantic communication.<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=540–7 |date=1999 |url=http://www.thepsychologist.org.uk/archive/archive_home.cfm/volumeID_12-editionID_46-ArticleID_133-getfile_getPDF/thepsychologist/psy_11_99_p540-547_happe.pdf |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 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 [[Diagnosis of Asperger syndrome#Differences from high-functioning autism|overlap between Asperger's, HFA, and non-syndromal autism]] is unclear.<ref>Validity of ASD subtypes:
*{{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 |doi=10.1590/S1516-44462006000500002 |pmid=16791390 |url=http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-44462006000500002&lng=en&nrm=iso&tlng=en}}
*{{cite journal |journal= J Autism Dev Disord |date=2008 |title= Examining the validity of autism spectrum disorder subtypes |author= Witwer AN, Lecavalier L |doi=10.1007/s10803-008-0541-2 |pmid=18327636}}</ref>
 
Some studies have reported diagnoses of autism in children due to a loss of language or social skills after 14 months of age, 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=Landa3/><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}} A partial update is in: {{cite journal |journal= World Psychiatry |date=2008 |volume=7 |issue=1 |pages=19–21 |title= Autism in infants: an update |author= Volkmar FR, Chawarska K |pmid=18458791 |pmc=2366821}}</ref>
 
The inability to identify biologically meaningful subpopulations has hampered research into causes.<ref>{{cite journal |journal=Pediatrics |date=2008 |volume=121 |issue=6 |pages=1225–9 |title= Autism and the environment: challenges and opportunities for research |author= Altevogt BM, Hanson SL, Leshner AI |doi=10.1542/peds.2007-3000 |pmid=18519493}}</ref> It has been proposed to classify autism using genetics as well as behavior, with the name ''Type 1 autism'' denoting rare autism cases that test positive for a mutation in the gene [[contactin associated protein-like 2]] (CNTNAP2).<ref>{{cite journal |journal= Am J Hum Genet |date=2008 |volume=82 |issue=1 |pages=7–9 |title= Unraveling autism |author= Stephan DA |doi=10.1016/j.ajhg.2007.12.003 |pmid=18179879}}</ref>
 
==Characteristics==
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/> 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.<ref name=London/>
 
===Social development===
People with autism 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>
 
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 more likely to communicate by manipulating another person's hand.<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>
 
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/>
 
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/>
 
===Communication===
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/> Joint attention seems to be necessary for functional speech, and deficits in joint attention seem to distinguish infants with ASD:<ref name=Johnson/> for example, they may look at a pointing hand instead of the pointed-at object,<ref name=Volkmar/><ref name=Tager-Flusberg/> and they consistently fail to point to "comment" about or "share" an experience at age-appropriate times.<ref name=Johnson/> 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>
 
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/>
 
===Repetitive behavior===
[[Image:Autistic-sweetiepie-boy-with-ducksinarow.jpg|thumb|A young boy with autism, and the precise line of toys he made]]
Autistic individuals display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (RBS-R)<ref name=RBS-R/> categorizes as follows.
*'''[[Stereotypy]]''' is apparently purposeless movement, such as hand flapping, head rolling, or body rocking.
*'''[[Compulsive behavior]]''' is intended and appears to follow rules, such as arranging objects in a certain way.
*'''Sameness''' is resistance to change; for example, insisting that the furniture not be moved or refusing to be interrupted.
*'''[[Ritual#Psychology|Ritualistic behavior]]''' involves the performance of daily activities the same way each time, such as an unvarying menu or dressing ritual. This is closely associated with sameness and an independent validation has suggested combining the two factors.<ref>{{cite journal |journal= J Autism Dev Disord |date=2007 |volume=37 |issue=5 |pages=855–66 |title= The Repetitive Behavior Scale-Revised: independent validation in individuals with autism spectrum disorders |author= Lam KSL, Aman MG |doi=10.1007/s10803-006-0213-z |pmid=17048092 |url=http://springerlink.com/content/v03747x60562638m/fulltext.html}}</ref>
*'''Restricted behavior''' is limited in focus, interest, or activity, such as preoccupation with a single television program.
*'''[[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/>
No single repetitive behavior seems to be specific to autism, but only autism appears to have an elevated pattern of occurrence and severity of these behaviors.<ref name=RBS-R>{{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>
 
===Other symptoms===
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}} {{cite journal |title=Erratum |quotes=no |date=2000 |journal= J Autism Dev Disord |volume=30 |issue=1 |pages=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>
A small fraction of individuals with ASD show unusual abilities, ranging from splinter skills such as the memorization of trivia to the extraordinarily rare talents of prodigious [[Savant syndrome|autistic savant]]s.<ref>{{cite web |author= Treffert DA |title= Savant syndrome: an extraordinary condition—a synopsis: past, present, future |publisher= Wisconsin Medical Society |date=2006 |url=http://www.wisconsinmedicalsociety.org/savant_syndrome/overview_of_savant_syndrome/synopsis |accessdate=2008-03-24}}</ref>
 
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> Differences are greater for under-responsivity (for example, walking into things) than for over-responsivity (for example, distress from loud noises) or for seeking (for example, rhythmic movements).<ref>{{cite journal |journal= J Autism Dev Disord |date=2008 |title= A meta-analysis of sensory modulation symptoms in individuals with autism spectrum disorders |author= Ben-Sasson A, Hen L, Fluss R, Cermak SA, Engel-Yeger B, Gal E |doi=10.1007/s10803-008-0593-3 |pmid=18512135}}</ref>
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 |volume=29 |issue=9 |pages=565–70 |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>
 
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]]. Although some children with autism also have [[gastrointestinal]] (GI) symptoms, 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> studies report conflicting results, and the relationship between GI problems and ASD is unclear.<ref name=CCD/>
 
[[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>
 
Parents of children with ASD have higher levels of stress.<ref>{{cite journal |journal=Pediatrics |date=2007 |volume=119 |issue=5 |pages=e1040–6 |title= Psychological functioning and coping among mothers of children with autism: a population-based study |author= Montes G, Halterman JS |doi=10.1542/peds.2006-2819 |pmid=17473077 |url=http://pediatrics.aappublications.org/cgi/content/full/119/5/e1040}}</ref> Siblings of children with ASD report greater admiration of and less conflict with the affected sibling; siblings of individuals with ASD have greater risk of negative well-being and poorer sibling relationships as adults.<ref>{{cite journal |journal= Ment Retard Dev Disabil Res Rev |date=2007 |volume=13 |issue=4 |pages=313–20 |title= Siblings of individuals with autism spectrum disorders across the life course |author= Orsmond GI, Seltzer MM |doi=10.1002/mrdd.20171 |pmid=17979200 |url=http://waisman.wisc.edu/family/pdf/MRDDRR-OrsmondSeltzer2007.pdf |format=PDF |accessdate=2008-04-17}}</ref>
 
==Causes==
{{main|Causes of autism}}
[[Image:Single Chromosome Mutations.png|thumb|left|Deletion (1), duplication (2) and inversion (3) are all [[chromosome abnormalities]] that have been implicated in autism.<ref name=Beaudet/>]]
Autism has a strong genetic basis, although the [[Heritability of autism|genetics of autism]] are complex and it is unclear whether ASD is explained more by multigene interactions or by rare [[mutation]]s with major effects.<ref name=Abrahams>{{cite journal |journal= Nat Rev Genet |year=2008 |volume=9 |issue=5 |pages=341–55 |title= Advances in autism genetics: on the threshold of a new neurobiology |author= Abrahams BS, Geschwind DH |doi=10.1038/nrg2346 |pmid=18414403}}</ref> Early studies of twins estimated [[heritability]] explains more than 90% of the risk of autism, assuming a shared environment and no other genetic or medical syndromes.<ref name=Freitag/> However, most of the mutations that increase autism risk have not been identified. Typically, autism cannot be traced to a [[Mendelian]] (single-gene) mutation or to single [[chromosome abnormalities]] such as [[Angelman syndrome]] or [[fragile X syndrome]], and none of the genetic syndromes associated with ASDs has been shown to selectively cause ASD.<ref name=Abrahams/> There may be significant interactions among mutations in several genes, or between the environment and mutated genes. Numerous candidate genes have been located, with only small effects attributable to any particular gene.<ref name=Abrahams/> The large number of autistic individuals with unaffected family members may result from [[copy number variation]]s (CNVs)—spontaneous [[Deletion (genetics)|deletions]] or [[gene duplication|duplications]] in genetic material during [[meiosis]].<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=445–9 |year=2007 |pmid=17363630 |doi=10.1126/science.1138659}}</ref> 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.<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=534–6 |pmid=17479094 |doi=10.1038/nm0507-534}}</ref>
 
All known [[teratogen]]s (agents that cause [[birth defect]]s) related to the risk of autism 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> Although evidence for other environmental causes is anecdotal and has not been confirmed by reliable studies,<ref name=Rutter/> extensive searches are underway.<ref name=Szpir>{{cite journal |journal= Environ Health Perspect |date=2006 |volume=114 |issue=7 |pages=A412–8 |title= Tracing the origins of autism: a spectrum of new studies |author= Szpir M |url=http://www.ehponline.org/members/2006/114-7/focus.html |pmid=16835042}}</ref> Environmental factors that have been claimed to contribute to or exacerbate autism, or may be important in future research, include certain foods, [[infectious disease]], [[heavy metals]], [[solvent]]s, [[diesel exhaust]], [[PCBs]], [[phthalates]] and [[phenol]]s used in [[plastic]] products, [[pesticide]]s, [[brominated flame retardant]]s, [[Ethanol|alcohol]], [[smoking]], [[illicit drug]]s, and [[vaccine]]s.<ref name=Newschaffer/> Although parents may first become aware of autistic symptoms in their child around the time of a routine vaccination, and parental concern about vaccines has led to a decreasing uptake of [[childhood immunizations]] and an increasing likelihood of [[Measles#Public health|measles outbreaks]], there is overwhelming scientific evidence showing no causal association between the [[MMR vaccine controversy|measles-mumps-rubella vaccine and autism]], and there is no scientific evidence that the vaccine preservative [[Thiomersal controversy|thiomersal helps cause autism]].<ref>Vaccines and autism:
*{{cite journal |journal= Can J Neurol Sci |date=2006 |volume=33 |issue=4 |pages=341–6 |title= Immunizations and autism: a review of the literature |author= Doja A, Roberts W |pmid=17168158}}
*{{cite journal |journal= Child Care Health Dev |year=2006 |volume=32 |issue=5 |pages=511–9 |title= Vaccines and the changing epidemiology of autism |author= Taylor B |doi=10.1111/j.1365-2214.2006.00655.x |pmid=16919130}}</ref>
 
==Mechanism==
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> The behaviors appear to have multiple pathophysiologies.<ref name=London/>
 
===Pathophysiology===
[[Image:Autismbrain.jpg|thumb|Autism affects many parts of the brain.]]
Autism appears to result from developmental factors that affect many or all functional brain systems,<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> and to disturb the course of brain development more than the final product.<ref name=Amaral>{{cite journal |journal=Trends Neurosci |date=2008 |volume=31 |issue=3 |pages=137–45 |title= Neuroanatomy of autism |author= [[David Amaral|Amaral DG]], Schumann CM, Nordahl CW |doi=10.1016/j.tins.2007.12.005 |pmid=18258309}}</ref> [[Neuroanatomical]] studies and the associations with teratogens strongly suggest that autism's mechanism includes alteration of brain development soon after conception.<ref name=Arndt/> This localized anomaly appears to start a cascade of pathological events in the brain that are significantly influenced by environmental factors.<ref>{{cite journal |journal= Brain Pathol |year=2007 |volume=17 |issue=4 |pages=422–33 |title= The neuropathology of autism |author= Casanova MF |doi=10.1111/j.1750-3639.2007.00100.x |pmid=17919128}}</ref> Although many major structures of the [[human brain]] have been implicated, almost all [[postmortem studies]] have been of individuals who also had mental retardation, making it difficult to draw conclusions.<ref name=Amaral/> Brain weight and volume and head circumference tend to be greater in autistic children.<ref>{{cite journal |journal= J Neurosci |date=2006 |volume=26 |issue=26 |pages=6897–906 |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> The cellular and molecular bases of pathological early overgrowth are not known, nor is it known whether the overgrown neural systems cause autism's characteristic signs. Current hypotheses include:
* An excess of [[neuron]]s that causes local overconnectivity in key brain regions.<ref>{{cite journal |journal=Neuron |date=2007 |volume=56 |issue=2 |pages=399-413 |title= Mapping early brain development in autism |author= Courchesne E, Pierce K, Schumann CM ''et al.'' |doi=10.1016/j.neuron.2007.10.016 |pmid=17964254}}</ref>
* Disturbed [[neuronal migration]] during early [[gestation]].<ref name=Schmitz/><ref name=Persico>{{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>
* Unbalanced excitatory-inhibitory networks.<ref name=Persico/>
* Abnormal formation of [[synapse]]s and [[dendritic spine]]s.<ref name=Persico/>


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> As [[autoantibodies]] have not been associated with pathology, are found in diseases other than ASD, and are not always present in ASD,<ref>{{cite journal |journal=Ann N Y Acad Sci |year=2007 |volume=1107 |pages=79–91 |title= Autoantibodies in autism spectrum disorders (ASD) |author= Wills S, Cabanlit M, Bennett J, Ashwood P, Amaral D, Van de Water J |doi=10.1196/annals.1381.009 |pmid=17804535}}</ref> the relationship between immune disturbances and autism remains unclear and controversial.<ref name=Schmitz>{{cite journal |journal= Neuropathol Appl Neurobiol |date=2008 |volume=34 |issue=1 |pages=4–11 |title= The neuropathology of autism: where do we stand? |author= Schmitz C, Rezaie P |doi=10.1111/j.1365-2990.2007.00872.x |pmid=17971078}}</ref>
{{SK}} Autistic spectrum disorder
==[[Autism overview|Overview]]==


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/> Also, some [[inborn errors of metabolism]] are associated with autism but probably account for less than 5% of cases.<ref name=Manzi/>
==[[Autism historical perspective|Historical Perspective]]==


The [[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:
==[[Autism classification|Classification]]==
*{{cite journal |journal= Sci Am |year=2006 |volume=295 |issue=5 |pages=62–9 |title= Broken mirrors: a theory of autism |author= [[Vilayanur S. Ramachandran|Ramachandran VS]], Oberman LM |pmid=17076085 |url=http://psy.ucsd.edu/chip/pdf/brokenmirrors_asd.pdf |format=PDF |accessdate=2008-04-17}}
*{{cite journal |journal=Curr Biol |date=2008 |volume=18 |issue=1 |pages=R13–8 |title= A mirror up to nature |author= Dinstein I, Thomas C, Behrmann M, Heeger DJ |doi=10.1016/j.cub.2007.11.004 |pmid=18177704}}</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> However, individuals with autism also have abnormal brain activation in many circuits outside the MNS<ref>{{cite journal |author= [[Uta Frith|Frith U]], Frith CD |date=2003 |title= Development and neurophysiology of mentalizing |journal= Philos Trans R Soc Lond B Biol Sci |volume=358 |issue=1431 |pages=459–73 |doi=10.1098/rstb.2002.1218 |pmid=12689373 |url=http://journals.royalsociety.org/content/pddyuvlhm88ebluf/fulltext.pdf |format=PDF}}</ref> and the MNS theory does not explain the normal performance of autistic children on imitation tasks that involve a goal or object.<ref>{{cite journal |journal= Q J Exp Psychol |date=2008 |volume=61 |issue=1 |pages=101–15 |title= Emulation and mimicry for social interaction: a theoretical approach to imitation in autism |author= Hamilton AFdC |doi=10.1080/17470210701508798 |pmid=18038342}}</ref>


A 2008 study of autistic adults found evidence for altered functional organization of the [[task-negative network]], a large-scale brain network involved in social and emotional processing, with intact organization of the [[task-positive network]], used in sustained attention and goal-directed thinking.<ref>{{cite journal |journal= Neuroimage |date=2008 |volume=38 |issue=4 |pages=1877–85 |title= The intrinsic functional organization of the brain is altered in autism |author= Kennedy DP, Courchesne E |doi=10.1016/j.neuroimage.2007.10.052 |pmid=18083565}}</ref> A 2008 brain-imaging study found a specific pattern of signals in the [[cingulate cortex]] which differs in individuals with ASD.<ref>{{cite journal |journal= Neuron |date=2008 |volume=57 |issue=3 |pages=463–73 |title= Self responses along cingulate cortex reveal quantitative neural phenotype for high-functioning autism |author= Chiu PH, Kayali MA, Kishida KT ''et al.'' |doi=10.1016/j.neuron.2007.12.020 |pmid=18255038 |laysummary=http://www.technologyreview.com/Biotech/20167/ |laysource= Technol Rev |laydate=2007-02-07}}</ref>
==[[Autism pathophysiology|Pathophysiology]]==


[[Image:FMRI.jpg|thumb|[[Functional magnetic resonance imaging]] provides some evidence for the underconnectivity theory of autism.]]
==[[Autism causes|Causes]]==
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= Cereb Cortex |year=2007 |volume=17 |issue=4 |pages=951-61 |title= Functional and anatomical cortical underconnectivity in autism: evidence from an FMRI study of an executive function task and corpus callosum morphometry |author= Just MA, Cherkassky VL, Keller TA, Kana RK, Minshew NJ |doi=10.1093/cercor/bhl006 |pmid=16772313 |url=http://cercor.oxfordjournals.org/cgi/content/full/17/4/951}}</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 |pmc=1803025}}</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=270–3 |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>


===Neuropsychology===
==[[Autism differential diagnosis|Differentiating Autism from other Disorders]]==
Two major categories of [[cognitive]] theories have been proposed about the links between autistic brains and behavior.


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/>
==[[Autism epidemiology and demographics|Epidemiology and Demographics]]==


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, 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> These theories map well from the underconnectivity theory of autism.
==[[Autism risk factors|Risk Factors]]==


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>{{cite journal |author= Happé F, Ronald A, [[Robert Plomin|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 |doi=10.1038/nn1770 |pmid=17001340}}</ref> 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>
==[[Autism screening|Screening]]==  


==Screening==
==[[Autism natural history, complications and prognosis|Natural History, Complications and Prognosis]]==
About half of parents of children with ASD notice their child's unusual behaviors by age 18 months, and about four-fifths notice by age 24 months.<ref name=Landa3/> 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:
*No [[babbling]] by 12 months.
*No [[Gesture|gesturing]] (pointing, waving goodbye, etc.) by 12 months.
*No single words by 16 months.
*No two-word spontaneous phrases (not including [[echolalia]]) by 24 months.
*Any loss of any language or social skills, at any age.<ref name=Filipek/>
The [[American Academy of Pediatrics]] recommends that all children be [[Screening (medicine)|screened]] for ASD at the 18- and 24-month well-child doctor visits, using autism-specific formal screening tests.<ref name=Johnson>{{cite journal |journal=Pediatrics |date=2007 |volume=120 |issue=5 |pages=1183–215 |title= Identification and evaluation of children with autism spectrum disorders |author= Johnson CP, Myers SM, Council on Children with Disabilities |doi=10.1542/peds.2007-2361 |pmid=17967920 |url=http://pediatrics.aappublications.org/cgi/content/full/120/5/1183 |laysummary=http://aap.org/advocacy/releases/oct07autism.htm |laysource=AAP |laydate=2007-10-29}}</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> Screening tools include the Modified Checklist for Autism in Toddlers (M-CHAT), the Early Screening of Autistic Traits Questionnaire, and the First Year Inventory; initial data on M-CHAT and its predecessor CHAT on children aged 18–30 months suggests that it is best used in a clinical setting and that it has low [[Sensitivity (tests)|sensitivity]] (many false-negatives) but good [[Specificity (tests)|specificity]] (few false-positives).<ref name=Landa3/> Screening tools designed for one culture's norms for behaviors like eye contact may be inappropriate for a different culture.<ref>{{cite journal |journal= Acta Paediatr |date=2008 |volume=97 |issue=5 |pages=539–40 |title= The challenge of screening for autism spectrum disorder in a culturally diverse society |author= Wallis KE, Pinto-Martin J |doi=10.1111/j.1651-2227.2008.00720.x |pmid=18373717}}</ref> Genetic screening for autism is generally still impractical.<ref name=McMahon/>


==Diagnosis==
==Diagnosis==
Diagnosis is based on behavior, not cause or mechanism.<ref name=London>{{cite journal |journal=Brain Pathol |year=2007 |volume=17 |issue=4 |pages=408–11 |title= The role of the neurobiologist in redefining the diagnosis of autism |author= London E |doi=10.1111/j.1750-3639.2007.00103.x |pmid=17919126}}</ref><ref>{{cite journal |journal=BMJ |date=2003 |volume=327 |issue=7413 |pages=488–93 |title= Diagnosis of autism |author= Baird G, Cass H, Slonims V |doi=10.1136/bmj.327.7413.488 |pmid=12946972 |url=http://www.bmj.com/cgi/content/full/327/7413/488}}</ref> 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://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://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>
[[Autism diagnostic criteria|Diagnostic Criteria]] | [[Autism history and symptoms|History and Symptoms]] | [[Autism physical examination|Physical Examination]] | [[Autism laboratory findings|Laboratory Findings]] | [[Autism CT|CT]] | [[Autism MRI|MRI]] | [[Autism other imaging findings|Other Imaging Findings]] | [[Autism other diagnostic studies|Other Diagnostic Studies]]
 
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/>
 
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]]<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> 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.<ref name=Landa3>{{cite journal |journal= Nat Clin Pract Neurol |date=2008 |volume=4 |issue=3 |pages=138–47 |title= Diagnosis of autism spectrum disorders in the first 3 years of life |author= Landa RJ |doi=10.1038/ncpneuro0731 |pmid=18253102}}</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=540–5 |title= How to diagnose autism |author= Dover CJ, Le Couteur A |doi=10.1136/adc.2005.086280 |pmid=17515625}}</ref> 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>
 
[[Clinical genetics]] evaluations are often done once ASD is diagnosed, particularly when other symptoms already suggest a genetic cause.<ref name=Caronna/> Although genetic technology allows clinical geneticists to link an estimated 40% of cases to genetic causes,<ref>{{cite journal |journal= Genet Med |date=2008 |volume=10 |issue=1 |pages=4–12 |title= Genetics evaluation for the etiologic diagnosis of autism spectrum disorders |author= Schaefer GB, Mendelsohn NJ |doi=10.1097/GIM.0b013e31815efdd7 |pmid=18197051 |laysummary=http://www.medicalnewstoday.com/articles/96448.php |laysource= Medical News Today |laydate=2008-02-07}}</ref> consensus guidelines in the U.S. and UK are limited to high-resolution chromosome and [[fragile X]] testing.<ref name=Caronna/> 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.<ref name=McMahon>{{cite journal |journal= Am J Med Genet C Semin Med Genet |date=2006 |volume=142C |issue=1 |pages=52–7 |title= Genetic counseling and ethical issues for autism |author= McMahon WM, Baty BJ, Botkin J |doi=10.1002/ajmg.c.30082 |pmid=16419100}}</ref> [[Metabolic]] and [[neuroimaging]] tests are sometimes helpful, but are not routine.<ref name=Caronna/>
 
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>
 
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= National Autistic Society |title= Diagnosis: how can it benefit me as an adult? |date=2005 |url=http://www.nas.org.uk/nas/jsp/polopoly.jsp?a=8018 |accessdate=2008-03-24}}</ref>
 
==Management==
{{main|Autism therapies}}
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,<ref name=CCD>{{cite journal |journal=Pediatrics |date=2007 |volume=120 |issue=5 |pages=1162–82 |title= Management of children with autism spectrum disorders |author= Myers SM, Johnson CP, Council on Children with Disabilities |doi=10.1542/peds.2007-2362 |pmid=17967921 |url=http://pediatrics.aappublications.org/cgi/content/full/120/5/1162 |laysummary=http://aap.org/advocacy/releases/oct07autism.htm |laysource=AAP |laydate=2007-10-29}}</ref> and often improve functioning and decrease symptom severity and maladaptive behaviors;<ref name=Rogers>{{cite journal |journal=J Clin Child Adolesc Psychol |date=2008 |volume=37 |issue=1 |pages=8–38 |title= Evidence-based comprehensive treatments for early autism |author= Rogers SJ, Vismara LA |doi=10.1080/15374410701817808 |pmid=18444052}}</ref> claims that intervention by age two to three years is crucial<ref>{{cite journal |journal= Harv Mag |date=2008 |volume=110 |issue=3 |pages= 27–31, 89–91 |title= A spectrum of disorders |author= Pettus A |url=http://harvardmagazine.com/2008/01/a-spectrum-of-disorders.html}}</ref> are not substantiated.<ref name=Howlin06/> Available approaches include [[applied behavior analysis]] (ABA), developmental models, [[TEACCH|structured teaching]], [[speech and language therapy]], [[social skills]] therapy, and [[occupational therapy]].<ref name=CCD/> Educational interventions have some effectiveness in children: intensive ABA treatment has demonstrated effectiveness in enhancing global functioning in preschool children<ref>{{cite journal |journal= Res Dev Disabil |date=2008 |title= Outcome of comprehensive psycho-educational interventions for young children with autism |author= Eikeseth S |doi=10.1016/j.ridd.2008.02.003 |pmid=18385012}}</ref>  and is well-established for improving intellectual performance of young children.<ref name=Rogers/> 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, [[Eric Schopler|Schopler E]] |doi=10.1023/A:1022931224934 |pmid=12757352}}</ref>
 
Many medications are used to treat problems associated with ASD.<ref>{{cite journal |journal= Harv Rev Psychiatry |date=2008 |volume=16 |issue=2 |pages=97–112 |title= Pharmacological treatment options for autism spectrum disorders in children and adolescents |author= Leskovec TJ, Rowles BM, Findling RL |doi=10.1080/10673220802075852 |pmid=18415882}}</ref> 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> Aside from antipsychotics,<ref>{{cite journal |journal= J Clin Invest |date=2008 |volume=118 |issue=1 |pages=6–14 |title= Antipsychotics in the treatment of autism |author= Posey DJ, Stigler KA, Erickson CA, McDougle CJ |doi=10.1172/JCI32483 |pmid=18172517 |url=http://jci.org/cgi/content/full/118/1/6}}</ref> there is scant reliable research about the effectiveness or safety of drug treatments for adolescents and adults with ASD.<ref>Lack of research on drug treatments:
*{{cite journal |journal= Aust Fam Physician |year=2007 |volume=36 |issue=9 |pages=741–4 |title= Children and autism—part 1—recognition and pharmacological management |author= Angley M, Young R, Ellis D, Chan W, McKinnon R |pmid=17915375 |url=http://www.racgp.org.au/Content/NavigationMenu/Publications/AustralianFamilyPhys/2007issues/afp200709/200709angley.pdf |format=PDF}}
*{{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 effect (medicine)|adverse effects]], and no known medication relieves autism's core symptoms of social and communication impairments.<ref name=Strock>{{cite paper |author=Strock M |date=2008 |title= Autism spectrum disorders (pervasive developmental disorders) |publisher= National Institute of Mental Health |url=http://nimh.nih.gov/health/publications/autism/complete-publication.shtml |accessdate=2008-03-24}}</ref><ref>{{cite journal |journal= Novartis Found Symp |date=2003 |volume=251 |pages= 235–44; discussion 245–9, 281–97 |title= Why have drug treatments been so disappointing? |author= Buitelaar JK |doi=10.1002/0470869380.ch14 |pmid=14521196}}</ref>


Although many [[Alternative therapies for developmental and learning disabilities|alternative therapies and interventions]] are available, few are supported by scientific studies.<ref name=Sigman/><ref>Lack of support for interventions:
==Treatment==
*{{cite journal |journal= Dev Med Child Neurol |date=2005 |volume=47 |issue=7 |pages=493–9 |title= Autism interventions: a critical update |author= Francis K |doi=10.1017/S0012162205000952 |pmid=15991872 |url=http://journals.cambridge.org/production/action/cjoGetFulltext?fulltextid=313204 |format=PDF}}
*{{cite journal |journal= J Autism Dev Disord |date=2008 |volume=38 |issue=2 |pages=353–61 |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}}
*{{cite journal |journal= Pediatr Ann |year=2007 |volume=36 |issue=8 |pages=497–8, 500–2, 504–5 |title= Scientifically unsupported therapies in the treatment of young children with autism spectrum disorders |author= Schechtman MA |pmid=17849608 |url=http://www.pediatricannalsonline.com/showPdf.asp?rID=23083 |format=PDF}}
</ref><ref name=Aman/> Treatment approaches have little 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 |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 |pmc=1350798}}</ref> Although most alternative treatments, such as [[melatonin]], have only mild adverse effects,<ref>{{cite journal |journal= Aust Fam Physician |year=2007 |volume=36 |issue=10 |pages=827–30 |title= Children and autism—part 2—management with complementary medicines and dietary interventions |author= Angley M, Semple S, Hewton C, Paterson F, McKinnon R |pmid=17925903 |url=http://www.racgp.org.au/Content/NavigationMenu/Publications/AustralianFamilyPhys/2007issues/afp200710/200710angley.pdf |format=PDF}}</ref> a 2008 study found that autistic boys on [[Casein#Casein-free_diet|casein-free diets]] have significantly thinner bones,<ref>{{cite journal |journal= J Autism Dev Disord |date=2008 |volume=38 |issue=5 |pages=848–56 |title= Reduced bone cortical thickness in boys with autism or autism spectrum disorder |author= Hediger ML, England LJ, Molloy CA, Yu KF, Manning-Courtney P, Mills JL |doi=10.1007/s10803-007-0453-6 |pmid=17879151 |laysummary=http://www.nih.gov/news/health/jan2008/nichd-29.htm |laysource= NIH News |laydate=2008-01-29}}</ref> and botched [[chelation therapy]] killed a five-year-old autistic boy in 2005.<ref>{{cite journal |journal=Pediatrics |date=2006 |volume=118 |issue=2 |pages=e534-6 |title= Deaths resulting from hypocalcemia after administration of edetate disodium: 2003–2005 |author= Brown MJ, Willis T, Omalu B, Leiker R |doi=10.1542/peds.2006-0858 |pmid=16882789 |url=http://pediatrics.aappublications.org/cgi/content/full/118/2/e534}}</ref>


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.<ref>{{cite journal |journal= Arch Pediatr Adolesc Med |date=2007 |volume=161 |issue=4 |pages=343–9 |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 |laysummary=http://www.hsph.harvard.edu/news/press-releases/2006-releases/press04252006.html |laysource= Harvard School of Public Health |laydate=2006-04-25}}</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> a 2008 U.S. study found a 14% average loss of annual income in families of children with ASD.<ref>{{cite journal |journal=Pediatrics |date=2008 |volume=121 |issue=4 |pages=e821–6 |title= Association of childhood autism spectrum disorders and loss of family income |author= Montes G, Halterman JS |doi=10.1542/peds.2007-1594 |pmid=18381511 |url=http://pediatrics.aappublications.org/cgi/content/full/121/4/e821}}</ref> After childhood, key treatment issues include residential care, job training and placement, sexuality, social skills, and estate planning.<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>
[[Autism medical therapy|Medical Therapy]] | [[Autism behavioral therapy|Behavioral Therapy]] | [[Autism cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Autism future or investigational therapies|Future or Investigational Therapies]]
 
==Case Studies==
==Prognosis==
[[Autism case study one|Case #1]]
There is no cure.<ref name=CCD/> Children recover occasionally, sometimes after intensive treatment and sometimes not; it is not known how often this happens.<ref name=Rogers/> 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=80–6 |doi=10.1111/j.1475-3588.2006.00432.x}}</ref> Although core difficulties remain, symptoms often become less severe in later childhood.<ref name=Howlin06>{{cite journal |author= Howlin P |title= Autism spectrum disorders |journal=Psychiatry |volume=5 |issue=9 |date=2006 |pages=320–4 |doi=10.1053/j.mppsy.2006.06.007}}</ref> Few high-quality studies address long-term [[prognosis]]. Some adults show modest improvement in communication skills, but a few 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 |url=http://waisman.wisc.edu/family/pdf/seltzer_trajectory.pdf |format=PDF |accessdate=2008-04-17}}</ref> Acquiring language before age six, 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> A 2005 Swedish study of 78 adults that did not exclude low IQ found worse prognosis; for example, only 4% achieved independence.<ref>{{cite journal |journal= J Autism Dev Disord |year=2005 |volume=35 |issue=3 |pages=351–60 |title= Autism after adolescence: population-based 13- to 22-year follow-up study of 120 individuals with autism diagnosed in childhood |author= Billstedt E, Gillberg C, Gillberg C |doi=10.1007/s10803-005-3302-5 |pmid=16119476}}</ref> A 2008 Canadian study of 48 young adults diagnosed with ASD as preschoolers found outcomes ranging through poor (46%), fair (32%), good (17%), and very good (4%); only 56% had ever been employed, most in volunteer, sheltered or part time work.<ref>{{cite journal |journal= J Autism Dev Disord |date=2008 |volume=38 |issue=4 |pages=739–47 |title= Young adult outcome of autism spectrum disorders |author= Eaves LC, Ho HH |doi=10.1007/s10803-007-0441-x |pmid=17764027}}</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/>
==Related Chapters==
 
* [[Pervasive developmental disorder|Pervasive Developmental Disorder]]
==Epidemiology==
* [[Asperger syndrome|Asperger Syndrome]]
{{Main|Epidemiology of autism}}
* [[Rett syndrome|Rett Syndrome]]
[[Image:US-autism-6-11-1996-2005.png|thumb|left|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]].]]
* [[Childhood disintegrative disorder|Childhood Disintegrative Disorder]]
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> because of inadequate data, these numbers may underestimate ASD's true prevalence.<ref name=Caronna>{{cite journal |journal= Arch Dis Child |date=2008 |volume=93 |issue=6 |pages=518–23 |title= Autism spectrum disorders: clinical and research frontiers |author= Caronna EB, Milunsky JM, Tager-Flusberg H |doi=10.1136/adc.2006.115337 |pmid=18305076}}</ref> [[PDD-NOS]] is the vast majority of ASD, [[Asperger's]] is about 0.3 per 1,000 and the remaining ASD forms 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> 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:
* [[PDD not otherwise specified|PDD Not Otherwise Specified (PDD-NOS)]]
*{{cite journal|author=Fombonne E|title=The prevalence of autism|journal=JAMA|date=2003|volume=289|issue=1|pages=87–9|pmid=12503982}}
* [[High-functioning autism|High Functioning Autism]]
*{{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= [[Professor Sir 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> 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/>
* [[Regressive autism|Regressive Autism]]
 
* [[Autism Diagnostic Interview-Revised]]
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 |url=http://archpedi.ama-assn.org/cgi/content/full/161/4/326}}</ref>
* [[Autism Diagnostic Observation Schedule]]
 
* [[Childhood Autism Rating Scale]]
Autism is associated with several other conditions:
* [[Refrigerator mother|Refrigerator Mother]]
*'''[[Genetic disorder]]s'''. About 10–15% of autism cases have an identifiable [[Mendelian]] (single-gene) condition, [[chromosome abnormality]], or other genetic syndrome,<ref>{{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> and ASD is associated with several genetic disorders.<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>
*'''[[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=3093–9 |pmid=11427137 |url=http://jama.ama-assn.org/cgi/content/full/285/24/3093}}</ref>
*'''[[Maleness]]'''. 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.<ref name=Newschaffer/>
*'''[[Epilepsy]]''', with variations in risk of epilepsy due to age, cognitive level, and type of language disorder.<ref>{{cite journal |journal=Epilepsia |date=2007 |volume=48 |issue= Suppl 9 |pages=33–5 |title= The autism-epilepsy connection |author= Levisohn PM |pmid=18047599}}</ref>
*Several '''[[metabolic defect]]s''', such as [[phenylketonuria]], are associated with autistic symptoms.<ref name=Manzi>{{cite journal |journal= J Child Neurol |date=2008 |volume=23 |issue=3 |pages=307–14 |title= Autism and metabolic diseases |author= Manzi B, Loizzo AL, Giana G, Curatolo P |doi=10.1177/0883073807308698 |pmid=18079313}}</ref>
 
==History==
 
{{See also|Sociological and cultural aspects of autism}}
 
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://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=201–8|title=The history of autism|author=Wolff S|doi=10.1007/s00787-004-0363-5|pmid=15365889}}</ref>
 
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=361–6|doi=10.1177/0957154X04044603|pmid=15386868}} The quote is a translation of Bleuler's 1910 original.</ref>
 
[[Image:kanner kl2.jpg|thumb|[[Leo Kanner]] introduced the label ''early infantile autism'' in 1943.]]
The word ''autism'' first took its modern sense in 1938 when [[Hans Asperger]] of the [[Vienna General Hospital|Vienna University Hospital]] adopted Bleuler's terminology "autistic psychopaths" in a lecture in German about child psychology.<ref>{{cite journal |journal= Wien Klin Wochenschr |year=1938 |volume=51 |pages=1314–7 |title= Das psychisch abnormale Kind |author= [[Hans Asperger|Asperger H]] |language=German}}</ref> Asperger was investigating a form of ASD now known as [[Asperger syndrome]], though for various reasons it was not widely recognized as a separate diagnosis until 1981.<ref name=Wolff/> [[Leo Kanner]] of the [[Johns Hopkins Hospital]] first used ''autism'' in its modern sense in English when he introduced the label ''early infantile autism'' in a 1943 report of 11 children with striking behavioral similarities.<ref name=Kanner1943>{{cite journal |author= [[Leo Kanner|Kanner L]] |title= Autistic disturbances of affective contact |journal= Nerv Child |volume=2 |pages=217–50 |date=1943}} {{cite journal |title=Reprint |quotes=no |date=1968 |journal= Acta Paedopsychiatr |volume=35 |issue=4 |pages=100–36 |pmid=4880460}}</ref> 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/> It is not known whether Kanner derived the term independently of Asperger.<ref name=Lyons>{{cite journal |journal= J Autism Dev Disord |year=2007 |volume=37 |issue=10 |pages=2022–3 |title= Asperger (1906–1980) and Kanner (1894–1981), the two pioneers of autism |author= Lyons V, Fitzgerald M |doi=10.1007/s10803-007-0383-3 |pmid=17922179 |url=http://springerlink.com/content/m55051670u35066p/fulltext.html}}</ref>
 
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=503–5 |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> As late as the mid-1970s there was little evidence of a genetic role in autism; now it is thought to be one of the most heritable of all psychiatric conditions.<ref>{{cite book |chapter= Genetic epidemiology of autism spectrum disorders |author= [[Peter Szatmari|Szatmari P]], Jones MB |pages=157–78 |title= Autism and Pervasive Developmental Disorders |edition = 2nd ed |editor= Volkmar FR |publisher= Cambridge University Press |year=2007 |isbn=0521549574}}</ref> 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=2007-06-30}}</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>{{cite news |author= Harmon A |title= How about not 'curing' us, some autistics are pleading |date=2004-12-20 |work= New York Times |url=http://www.nytimes.com/2004/12/20/health/20autism.html |accessdate=2007-11-07}}</ref>
 
==References==
{{reflist|2}}


{{Pervasive developmental disorders}}
{{Pervasive developmental disorders}}
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{{WikiDoc Sources}}


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[[Category:Mature chapter]]
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[[Category:Psychiatry]]
[[Category:Neurology]]
[[Category:Communication disorders]]
[[Category:Communication disorders]]
[[Category:Neurological disorders]]
[[Category:Neurological disorders]]
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Risk calculators and risk factors for Autism

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2] ; Syed Hassan A. Kazmi BSc, MD [3] ; Iqra Qamar M.D.[4] ; Akshun Kalia M.B.B.S.[5] ; Chandrakala Yannam, MD [6] Sadaf Sharfaei M.D.[7]

Synonyms and keywords: Autistic spectrum disorder

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Autism from other Disorders

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Criteria | History and Symptoms | Physical Examination | Laboratory Findings | CT | MRI | Other Imaging Findings | Other Diagnostic Studies

Treatment

Medical Therapy | Behavioral Therapy | Cost-Effectiveness of Therapy | Future or Investigational Therapies

Case Studies

Case #1

Related Chapters

Template:Pervasive developmental disorders

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