Autism history and symptoms
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Autism is distinguished by a pattern of symptoms rather than one single symptom. The main characteristics are impairments in social interaction, impairments in communication, restricted interests and repetitive behavior. Other aspects, such as atypical eating, are also common but are not essential for diagnosis. Individual symptoms of autism occur in the general population and appear not to associate highly, without a sharp line separating pathological severity from common traits.
History
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.
Autism Spectrum Quotient
The Autism Spectrum Quotient, or AQ, is a questionnaire published in 2001 by Simon Baron-Cohen and his colleagues at the Autism Research Centre in Cambridge, UK. Consisting of fifty questions, it aims to investigate whether normal adults have symptoms of autism or one of the other autism spectrum disorders. The test was popularised by Wired Magazine in December 2001 when published alongside their article, "The Geek Syndrome" and is commonly used for self diagnosis of Asperger Syndrome.[1]
- Format
The test consists of fifty statements, each of which is in a forced-choice format. Each question allows the subject to indicate "Definitely agree", "Slightly agree", "Slightly disagree" or "Definitely disagree". Approximately half the questions are worded to elicit an "agree" response from normal individuals, and half to elicit a "disagree" response. The subject scores one point for each question which is answered "autistically" either slightly or definitely. The questions cover five different domains associated with the autism spectrum: social skills; communication skills; imagination; attention to detail; and attention switching/tolerance of change.
- Use as a Diagnostic Tool
In the initial trials of the test,[2] the average score in the control group was 16.4, with men scoring slightly higher than women (about 17 versus about 15). 80% of adults diagnosed with autism spectrum disorders scored 32 or more, compared with only 2% of the control group. The authors cited a score of 32 or more as indicating "clinically significant levels of autistic traits". However, although the test is popularly used for self-diagnosis of Asperger Syndrome, the authors caution that it is not intended to be diagnostic, and advise that anyone who obtains a high score and is suffering some distress should seek professional medical advice before jumping to any conclusions.
A further research paper[1] indicated that the questionnaire could be used for screening in clinical practice, with scores of 26 or lower indicating that a diagnosis of Asperger Syndrome can effectively be ruled out.
Common Symptoms
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 neurotypicals as leaving her feeling "like an anthropologist on Mars".[3]
Social impairments become apparent early in childhood and continue through adulthood. Autistic people are prone to commit social faux pas because of an inability to predict others' reactions. Autistic infants show less attention to social stimuli, smile and look at others less often, may also neglect social niceties like knocking or returning a greeting and respond less to their own name. Similarly, they may be overly trusting or paranoid of strangers. It may be best summed up as an inability to understand/perceive the intent or emotional wants and needs of others around them. 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. This leads others to conclude that they are shy, uninterested or evasive. 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. They may appear somewhat removed or dissociated or dreamy at times, especially when in sensory overload or from a perception of extreme social pressure. However, they do form attachments to their primary caregivers.[4] They display moderately less attachment security than usual, although this feature disappears in children with higher mental development or less severe ASD.[5] Older children and adults with ASD perform worse on tests of face and emotion recognition.[6]
Unlike those with low-functioning autism, people with high-functioning autism are not mentally retarded; persons with high-functioning autism have an IQ at the average to above-average range. High-functioning autism (HFA) is an informal term applied to individuals with autism, an IQ of 80 or above, and the ability to speak, read, and write.[7] HFA may simply refer to autistic people who have normal overall intelligence; that is, are not cognitively challenged.[8] Although they may have an adequate vocabulary, they may have a delay in communicating events and use less emotional content in their speech. They may also appear not to notice non-verbal cues from others such as when others have become bored with the topic of conversation they appear oblivious and continue.
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.
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.
Generally, there are difficulties with social interaction. This might not adversely affect their ability to interact with others on a day-to-day basis at a basic working level, although they may be seen as being overly serious or earnest, and as being without any "small talk" in conversation. In many instances though, these individuals have such severe social delays and difficulties that interaction within a "normal" social setting can be severely hampered.
They may have difficulty initiating love and friendship relationships, often being rejected because potential partners perceive them as being either too "nerdy" or too intelligent. This can lead to low self esteem or loneliness, which further impairs their ability to find meaningful companionship.
People may label HFA people as "oddballs" or worse, and HFA people can easily become the target of bullying. This can be especially true from primary school through the late teens. Young, intelligent HFA people usually do best by seeking out the company of their intellectual peers or by joining hobby groups, while avoiding their age-group peers. Exposure to an age equivalent peer group within the autism spectrum on a regular basis can be especially beneficial.
Given the proven crucial role of body language in job interviews, lack of eye contact in such a situation may be perceived by potential employers as indicating that the candidate is "not telling the truth" or "uninterested in the job", and thus lead to a cumulative difficulty in finding employment. Attending social and business events to network is also proven to play a crucial role in job hunting, but events such as these are the type that HFA people usually avoid due to their unease with the complex social interactions required. Difficulties with such pre-employment factors may contribute to comparative poverty, although intelligent HFA adults can usually find a good job if they can specialise in their area of interest. Once in a good job, however, their talents may lead to promotion and they may find themselves in a new job description that does not fit their personality.
Some may have minor to moderate difficulty with motor skills and co-ordination. This may manifest itself as mere clumsiness or awkwardness but in some instances can be found at a level where the child is a danger to themselves (this is especially true when younger), but may manifest itself in adulthood by "bumping into walls" and doors or other people without intention. "Sensory motor dysfunction" is a comorbid diagnosis that is increasingly being associated with individuals with HFA. Many of these motor skills and functional issues can be helped through the use of regular physical therapy.
Alongside deficiencies they may simultaneously benefit from some of the more positive aspects of autism. For example, they may have the ability to focus intensely and for long periods on a difficult problem. There is often an enhanced learning ability, although this often is not applied to subjects they are uninterested in. They often present no problems in a supportive, well-resourced educational institution and often do well academically if they can be stimulated by good teachers. People with HFA often have intense and deep knowledge of an obscure or difficult subject and a passion for pursuing it in an organized and scholarly manner.
They are usually intelligent, gifted, honest, hard workers when interested in a task and excellent problem solvers. People with HFA are thought to become excellent scientists and engineers or enter other professions where painstaking, methodical analysis is required. Some believe this particular assertion is a stereotype, as some HFA adults tend to struggle with the traditional work setting and the surrounding societally accepted ways of behaving.
Speech and diction can be unusually precise in some individuals with HFA but this may be delayed or awkward in many other individuals.
Communication
About a third to a half of individuals with autism do not develop enough natural speech to meet their daily communication needs.[9] 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) or reverse pronouns. Joint attention seems to be necessary for functional speech, and deficits in joint attention seem to distinguish infants with ASD: for example, they may look at a pointing hand instead of the pointed-at object, and they consistently fail to point to "comment" about or "share" an experience at age-appropriate times. Autistic children may have difficulty with imaginative play and with developing symbols into language.[10][11]
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.
Repetitive Behavior
Autistic individuals display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (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.
- 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.[12]
- 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.[13]
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.[14]
Autistic people are prone to commit social faux pas because of an inability to predict others' reactions. They may also neglect social niceties like knocking or returning a greeting. Similarly, they may be overly trusting or paranoid of strangers. It may be best summed up as an inability to understand/perceive the intent or emotional wants and needs of others around them.
They may appear somewhat removed or dissociated or dreamy at times, especially when in sensory overload or from a perception of extreme social pressure. They may make little eye contact, leading others to conclude that they are shy, uninterested or evasive.
Unlike those with low-functioning autism, people with high-functioning autism are not mentally retarded; persons with high-functioning autism have an IQ at the average to above-average range. High-functioning autism (HFA) is an informal term applied to individuals with autism, an IQ of 80 or above, and the ability to speak, read, and write.[15] HFA may simply refer to autistic people who have normal overall intelligence; that is, are not cognitively challenged.[16] Although they may have an adequate vocabulary, they may have a delay in communicating events and use less emotional content in their speech. They may also appear not to notice non-verbal cues from others such as when others have become bored with the topic of conversation they appear oblivious and continue.
As with people elsewhere on the autistic spectrum, people with high-functioning autism generally prefer routine and order, and this usually begins in early childhood. They may, for example, write an alphabetized index of their comic book collection, or they may stick to a limited wardrobe.
Generally, there are difficulties with social interaction. This might not adversely affect their ability to interact with others on a day-to-day basis at a basic working level, although they may be seen as being overly serious or earnest, and as being without any "small talk" in conversation. In many instances though, these individuals have such severe social delays and difficulties that interaction within a "normal" social setting can be severely hampered.
They may have difficulty initiating love and friendship relationships, often being rejected because potential partners perceive them as being either too "nerdy" or too intelligent. This can lead to low self esteem or loneliness, which further impairs their ability to find meaningful companionship.
People may label HFA people as "oddballs" or worse, and HFA people can easily become the target of bullying. This can be especially true from primary school through the late teens. Young, intelligent HFA people usually do best by seeking out the company of their intellectual peers or by joining hobby groups, while avoiding their age-group peers. Exposure to an age equivalent peer group within the autism spectrum on a regular basis can be especially beneficial.
Given the proven crucial role of body language in job interviews, lack of eye contact in such a situation may be perceived by potential employers as indicating that the candidate is "not telling the truth" or "uninterested in the job", and thus lead to a cumulative difficulty in finding employment. Attending social and business events to network is also proven to play a crucial role in job hunting, but events such as these are the type that HFA people usually avoid due to their unease with the complex social interactions required. Difficulties with such pre-employment factors may contribute to comparative poverty, although intelligent HFA adults can usually find a good job if they can specialise in their area of interest. Once in a good job, however, their talents may lead to promotion and they may find themselves in a new job description that does not fit their personality.
Some may have minor to moderate difficulty with motor skills and co-ordination. This may manifest itself as mere clumsiness or awkwardness but in some instances can be found at a level where the child is a danger to themselves (this is especially true when younger), but may manifest itself in adulthood by "bumping into walls" and doors or other people without intention. "Sensory motor dysfunction" is a comorbid diagnosis that is increasingly being associated with individuals with HFA. Many of these motor skills and functional issues can be helped through the use of regular physical therapy.
Some may also nurture a complex habitual movement (termed "stimming") at which they become adept, for example, pen spinning, while otherwise being prone to clumsiness.
They do not lack empathy (although they may have difficulty expressing it), and can thus enjoy films and stories with emotional content. Some may gain the bulk of their insight into why people behave the way they do through watching movies that provide a forceful and musically-cued "capsule lesson" in human emotions (e.g. melodramas).
Alongside deficiencies they may simultaneously benefit from some of the more positive aspects of autism. For example, they may have the ability to focus intensely and for long periods on a difficult problem. There is often an enhanced learning ability, although this often is not applied to subjects they are uninterested in. They often present no problems in a supportive, well-resourced educational institution and often do well academically if they can be stimulated by good teachers. People with HFA often have intense and deep knowledge of an obscure or difficult subject and a passion for pursuing it in an organized and scholarly manner.
They are usually intelligent, gifted, honest, hard workers when interested in a task and excellent problem solvers. People with HFA are thought to become excellent scientists and engineers or enter other professions where painstaking, methodical analysis is required. Some believe this particular assertion is a stereotype, as some HFA adults tend to struggle with the traditional work setting and the surrounding societally accepted ways of behaving.
Speech and diction can be unusually precise in some individuals with HFA but this may be delayed or awkward in many other individuals.
Less Common Symptoms
Autistic individuals may have symptoms that are independent of the diagnosis, but that can affect the individual or the family.[17] Unusual responses to 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.[18] 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).[19] Several studies have reported associated motor problems that include poor muscle tone, poor motor planning, and toe walking; ASD is not associated with severe motor disturbances.[20]
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;[13] 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;[21] studies report conflicting results, and the relationship between GI problems and ASD is unclear. 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 awakenings, and early morning awakenings. Dominick et al. found that about two-thirds of children with ASD had a history of sleep problems.[13]
Parents of children with ASD have higher levels of stress.[22] 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.[23]
Behaviorally, certain characteristics identify the autism spectrum. The type, severity and/or number of autistic traits present determines the severity of autism in the individual. These autistic traits may be beneficial for some disciplines like science, mathematics, engineering and computer programming. Some autistic individuals might show a marked proficiency in rote memorization which may help learn the foundation of these subjects; however, the exceptionally good aptitude (in these subjects) of high functioning autistic spectrum persons may be due to their ability to readily identify patterns and apply them consistently to new situations outside of established knowledge or teaching. These savant skills, although popularly considered to be a major part of autistic disorders, are evident only in a small fraction of autistic individuals, with estimates of the fraction ranging from 0.5% to 10%.[24]
Diagnostic Criteria
When the rising prevalence of autism spectrum disorders sparked research in the late 1990s, medical opinion initially attributed the increase to improved diagnostic screening or changes in the definition of autism. In 1994, the fourth major revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) was published with updated criteria for the diagnosis of autism and autism spectrum disorders.[25] Professional medical associations, including the American Academy of Pediatrics, say that this revision was an important factor in increasing the apparent prevalence of autism and a 2005 study by Mayo Clinic researchers found increases in autistic spectrum disorder diagnoses followed the revisions in DSM criteria and changes in funding for special education programs.[26]
An increased awareness of autistic spectrum disorders by parents and pediatricians may have also led to increased reporting of Autism due to 'case substitution', which occurs when children with other disorders are identified as autistic.[27] This misdiagnosis may occur for several reasons including an increase in government funding for care of children diagnosed as autistic, but not for children with a similar degree of disability and need. If this is occurring, it means that children who in the past would probably have been diagnosed as having a learning disability or a psychiatric disorder, or not diagnosed at all, are recorded as cases of autistic spectrum disorder.[28]
Children who are not primarily autistic, e.g. those with Fragile-X Syndrome (with characteristics that fit the criteria for autism) and even Down's Syndrome may have the diagnostic group with the best funding assigned. Dr. Fred Volkmar, a Yale University autism researcher, has said that "diagnostic substitution" was prompted by better services for autism.[29]
Care should be exercised when attempting to determine whether a person with autism is "high functioning" or "low functioning" based on an IQ score since it is sometimes difficult to measure IQ in autistic persons accurately using standard measurement instruments. The amount of language processing necessary on the tests and the large quantity of verbal instructions involved in the testing process even on the "non-verbal" portion of standard intelligence measures can produce a misleadingly low score. There can be a significant difference between an autistic person's measured IQ scores when comparing standard testing methods and a truly non-verbal method such as the Leiter-R.
A diagnosis of high-functioning autism exists in neither the DSM-IV-TR nor the ICD-10, which have diagnoses of autistic disorder and childhood autism respectively. Analogous to high-functioning when applied to schizophrenia and other psychiatric disorders, the term high-functioning autism started out as a shorthand to describe diagnosed autistic individuals who could nevertheless speak and carry on with many day-to-day activities like eating and dressing independently. Low-functioning autism was the conceptual opposite. Researchers then began using high-functioning autism as a quasi-diagnostic label itself, along with low-functioning autism and sometimes also Asperger's Syndrome, to distinguish relative levels of adaptation and development.
There is some evidence that the label has wrongly become a catch-all diagnosis for badly-behaved children. In 2000 in the UK, the lead clinician and autism specialist at Northgate and Prudhoe NHS Trust in Morpeth, Dr Tom Berney, published a paper commenting on this. He wrote in the prestigious British Journal of Psychiatry:- "There is a risk of the diagnosis of autism being extended to include anyone whose odd and troublesome personality does not readily fit some other category. Such over-inclusion is likely to devalue the diagnosis to a meaningless label."
References
- ↑ 1.0 1.1 M. Woodbury-Smith, J. Robinson and S. Baron-Cohen, Screening adults for Asperger Syndrome using the AQ : diagnostic validity in clinical practice, Journal of Autism and Developmental Disorders 35 331-335 (2005)
- ↑ S. Baron-Cohen, S. Wheelwright, R. Skinner, J. Martin and E. Clubley, The Autism Spectrum Quotient (AQ) : Evidence from Asperger Syndrome/High Functioning Autism, Males and Females, Scientists and Mathematicians, Journal of Autism and Developmental Disorders 31, 5-17 (2001)
- ↑ Sacks O (1995). An Anthropologist on Mars: Seven Paradoxical Tales. Knopf. ISBN 0679437851.
- ↑ Sigman M, Dijamco A, Gratier M, Rozga A (2004). "Early detection of core deficits in autism". Ment Retard Dev Disabil Res Rev. 10 (4): 221–33. doi:10.1002/mrdd.20046. PMID 15666338.
- ↑ Rutgers AH, Bakermans-Kranenburg MJ, van IJzendoorn MH, van Berckelaer-Onnes IA (2004). "Autism and attachment: a meta-analytic review". J Child Psychol Psychiatry. 45 (6): 1123–34. doi:10.1111/j.1469-7610.2004.t01-1-00305.x. PMID 15257669.
- ↑ Sigman M, Spence SJ, Wang AT (2006). "Autism from developmental and neuropsychological perspectives". Annu Rev Clin Psychol. 2: 327–55. doi:10.1146/annurev.clinpsy.2.022305.095210. PMID 17716073.
- ↑ Study Provides Evidence That Autism Affects Functioning of Entire Brain: Previous View Held Autism Limited to Communication, Social Behavior, and Reasoning National Institute of Health News, Aug. 16, 2006
- ↑ Validity and Neuropsychological Characterization of Asperger Syndrome: Convergence with Nonverbal Learning Disabilities Syndrome A. Klin et al (1995) The Journal of Child Psychology and Psychiatry and Allied Disciplines, Vol. 36, No. 7, pp. 1127-1140, 1995. Reprinted with permission from Cambridge University Press. See section titled "Validity of Asperger syndrome"
- ↑ Noens I, van Berckelaer-Onnes I, Verpoorten R, van Duijn G (2006). "The ComFor: an instrument for the indication of augmentative communication in people with autism and intellectual disability". J Intellect Disabil Res. 50 (9): 621–32. doi:10.1111/j.1365-2788.2006.00807.x. PMID 16901289.
- ↑ Landa R (2007). "Early communication development and intervention for children with autism". Ment Retard Dev Disabil Res Rev. 13 (1): 16–25. doi:10.1002/mrdd.20134. PMID 17326115.
- ↑ Tager-Flusberg H, Caronna E (2007). "Language disorders: autism and other pervasive developmental disorders". Pediatr Clin North Am. 54 (3): 469–81. doi:10.1016/j.pcl.2007.02.011. PMID 17543905.
- ↑ Lam KSL, Aman MG (2007). "The Repetitive Behavior Scale-Revised: independent validation in individuals with autism spectrum disorders". J Autism Dev Disord. 37 (5): 855–66. doi:10.1007/s10803-006-0213-z. PMID 17048092.
- ↑ 13.0 13.1 13.2 Dominick KC, Davis NO, Lainhart J, Tager-Flusberg H, Folstein S (2007). "Atypical behaviors in children with autism and children with a history of language impairment". Res Dev Disabil. 28 (2): 145–62. doi:10.1016/j.ridd.2006.02.003. PMID 16581226.
- ↑ Bodfish JW, Symons FJ, Parker DE, Lewis MH (2000). "Varieties of repetitive behavior in autism: comparisons to mental retardation". J Autism Dev Disord. 30 (3): 237–43. doi:10.1023/A:1005596502855. PMID 11055459.
- ↑ Study Provides Evidence That Autism Affects Functioning of Entire Brain: Previous View Held Autism Limited to Communication, Social Behavior, and Reasoning National Institute of Health News, Aug. 16, 2006
- ↑ Validity and Neuropsychological Characterization of Asperger Syndrome: Convergence with Nonverbal Learning Disabilities Syndrome A. Klin et al (1995) The Journal of Child Psychology and Psychiatry and Allied Disciplines, Vol. 36, No. 7, pp. 1127-1140, 1995. Reprinted with permission from Cambridge University Press. See section titled "Validity of Asperger syndrome"
- ↑ Filipek PA, Accardo PJ, Baranek GT; et al. (1999). "The screening and diagnosis of autistic spectrum disorders". J Autism Dev Disord. 29 (6): 439–84. doi:10.1023/A:1021943802493. "Erratum". J Autism Dev Disord. 30 (1): 81. 2000. doi:10.1023/A:1017256313409. PMID 10638459. Unknown parameter
|quotes=ignored (help) This paper represents a consensus of representatives from nine professional and four parent organizations in the U.S. - ↑ Rogers SJ, Ozonoff S (2005). "Annotation: what do we know about sensory dysfunction in autism? A critical review of the empirical evidence". J Child Psychol Psychiatry. 46 (12): 1255–68. doi:10.1111/j.1469-7610.2005.01431.x. PMID 16313426.
- ↑ Ben-Sasson A, Hen L, Fluss R, Cermak SA, Engel-Yeger B, Gal E (2008). "A meta-analysis of sensory modulation symptoms in individuals with autism spectrum disorders". J Autism Dev Disord. doi:10.1007/s10803-008-0593-3. PMID 18512135.
- ↑ Ming X, Brimacombe M, Wagner GC (2007). "Prevalence of motor impairment in autism spectrum disorders". Brain Dev. 29 (9): 565–70. doi:10.1016/j.braindev.2007.03.002. PMID 17467940.
- ↑ Erickson CA, Stigler KA, Corkins MR, Posey DJ, Fitzgerald JF, McDougle CJ (2005). "Gastrointestinal factors in autistic disorder: a critical review". J Autism Dev Disord. 35 (6): 713–27. doi:10.1007/s10803-005-0019-4. PMID 16267642.
- ↑ Montes G, Halterman JS (2007). "Psychological functioning and coping among mothers of children with autism: a population-based study". Pediatrics. 119 (5): e1040–6. doi:10.1542/peds.2006-2819. PMID 17473077.
- ↑ Orsmond GI, Seltzer MM (2007). "Siblings of individuals with autism spectrum disorders across the life course" (PDF). Ment Retard Dev Disabil Res Rev. 13 (4): 313–20. doi:10.1002/mrdd.20171. PMID 17979200. Retrieved 2008-04-17.
- ↑ Treffert DA (2007). "Savant syndrome: an extraordinary condition—a synopsis: past, present, future". Wisconsin Medical Society. Retrieved 2007-09-19.
- ↑ Tidmarsh L, Volkmar FR (2003). "Diagnosis and epidemiology of autism spectrum disorders". Can J Psychiatry. 48 (8): 517–25. PMID 14574827.
- ↑ Barbaresi WJ, Katusic SK, Colligan RC, Weaver AL, Jacobsen SJ (2005). "The incidence of autism in Olmsted County, Minnesota, 1976-1997: results from a population-based study". Arch Pediatr Adolesc Med. 159 (1): 37–44. doi:10.1001/archpedi.159.1.37. PMID 15630056.
- ↑ Shattuck PT (2006). "The contribution of diagnostic substitution to the growing administrative prevalence of autism in US special education". Pediatrics. 117 (4): 1028–37. doi:10.1542/peds.2005-1516. PMID 16585296. Lay summary (2006-04-03).
- ↑ Pettus A (2008). "A spectrum of disorders". Harv Mag. 110 (3): 27–31, 89–91.
- ↑ "Uncovering autism's mysteries: Is there more autism? Or just a new definition?". Associated Press. 2003-03-02. Retrieved 2007-12-30.
'Autism is kind of a fashionable diagnosis,' Volkmar said. 'Everybody's interested in getting better services.'