Autism

Updated: Nov 15, 2016
  • Author: James Robert Brasic, MD, MPH; Chief Editor: Caroly Pataki, MD  more...
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Overview

Practice Essentials

Autism spectrum disorder (ASD) manifests in early childhood and is characterized by qualitative abnormalities in social interactions, markedly aberrant communication skills, and restricted repetitive behaviors, interests, and activities (RRBs).

Signs and symptoms

Behavioral and developmental features that suggest autism include the following:

  • Developmental regression
  • Absence of protodeclarative pointing
  • Abnormal reactions to environmental stimuli
  • Abnormal social interactions
  • Absence of smiling when greeted by parents and other familiar people
  • Absence of typical responses to pain and physical injury
  • Language delays and deviations
  • Susceptibility to infections and febrile illnesses
  • Absence of symbolic play
  • Repetitive and stereotyped behavior

Regular screening of infants and toddlers for symptoms and signs of autistic disorder is crucial because it allows for early referral of patients for further evaluation and treatment. Siblings of children with autism are at risk for developing traits of autism and even a full-blown diagnosis of autism. Therefore, siblings should also undergo screening not only for autism-related symptoms but also for language delays, learning difficulties, social problems, and anxiety or depressive symptoms. [1]

Having parents fill out the Autism Screening Checklist can identify children who merit further assessment for possible autism. See the image below for a printable version of the checklist.

The significance of answers to individual Autism S The significance of answers to individual Autism Screening Checklist items is as follows: Item 1- A "yes" occurs in healthy children and children with some pervasive developmental disorders; a "no" occurs in children with autism, Rett syndrome, and other developmental disorders. Item 2 - A "yes" occurs in healthy children, not children with autism. Item 3 - A "yes" occurs in healthy children and children with Asperger syndrome (ie, high-functioning autism); a "no" occurs in children with Rett syndrome; children with autism may elicit a "yes" or a "no"; some children with autism never speak; some children with autism may develop speech normally and then experience a regression with the loss of speech. Item 4 - A "yes" occurs in healthy children and children with Asperger syndrome and some other pervasive developmental disorders; a "no" occurs in children with developmental disorders; children with autism may elicit a "yes" or a "no." Items 5-10 - Scores of "yes" occur in some children with autism and in children with other disorders. Item 11 – A "yes" occurs in healthy children; a "no" occurs in some children with autism and in children with other disorders. Items 12, 13 - Scores of "yes" occur in some children with autism and in children with other disorders. Items 14-19 - Scores of "yes" occur in children with schizophrenia and other disorders, not in children with autism, Asperger syndrome, or other autism spectrum disorders. The higher the total score for items 5-10, 12, and 13 on the Autism Screening Checklist, the more likely the presence of an autism spectrum disorder.

See Clinical Presentation for more detail.

Diagnosis

Examination for patients with suspected autistic spectrum disorder may include the following findings:

  • Abnormal motor movements (eg, clumsiness, awkward walk, hand flapping, tics)
  • Dermatologic anomalies (eg, aberrant palmar creases)
  • Abnormal head circumference (eg, small at birth, increased from age 6 months to 2 years, [2] normal in adolescence [3] )
  • Orofacial, extremity, and head/trunk stereotypies (eg, purposeless, repetitive, patterned motions, postures, and sounds)
  • Self-injurious behaviors (eg, picking at the skin, self-biting, head punching/slapping)
  • Physical abuse inflicted by others (eg, parents, teachers)
  • Sexual abuse: External examination of genitalia is appropriate; if bruises and other evidence of trauma are present, pelvic and rectal examinations may be indicated

Diagnostic criteria

The definition of ASD in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) encompasses the previous manual's autistic disorder (autism), Asperger's disorder, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified. ASD is characterized by the following [4] :

  • Deficits in social communication and social interaction
  • Restricted repetitive behaviors, interests, and activities (RRBs)

These symptoms are present from early childhood and limit or impair everyday functioning. Both components are required for diagnosis of ASD.

Testing

There are no blood studies recommended for the routine assessment of ASD. Although several metabolic abnormalities have been identified in investigations of people with autism (eg, elevated 5-HT, reduced serum biotinidase, abnormal neurotransmitter functions, impaired phenolic amines metabolism), a metabolic workup should be considered on an individual basis. No biologic markers for autism currently exist.

Studies that may be helpful in the evaluation of autistic disorder include the following:

  • EEG: To exclude seizure disorder, acquired aphasia with convulsive disorder (Landau-Kleffner syndrome), biotin-responsive infantile encephalopathy, related conditions
  • Psychophysiologic assessment: To show lack of response habituation to repeatedly presented stimuli (in respiratory period, electrodermal activity, vasoconstrictive peripheral pulse amplitude response); auditory overselectivity may be seen
  • Polysomnography: To identify sleep disorders and to demonstrate seizure discharges

Neuroimaging studies

There is currently no clinical evidence to support the role of routine clinical neuroimaging in the diagnostic evaluation of autism, even in the presence of megalencephaly. [1] Although characteristic abnormalities have been identified, no single finding is diagnostic.

The following imaging techniques have yielded inconsistent results in evaluating autism:

  • MRI with or without diffusion tensor imaging
  • CT scanning
  • PET scanning
  • SPECT scanning

See Workup for more detail.

Management

The established therapies for autistic disorder are nonpharmacologic and may include individual intensive interventions. Individuals with autism spectrum disorder and unspecified pervasive developmental disorder typically benefit from behaviorally oriented therapeutic programs developed specifically for this population. Autistic children should be placed in these specialized programs as soon as the diagnosis is suspected.

Nonpharmacologic therapy

  • Intensive individual special education
  • Speech, behavioral, occupational, and physical therapies (eg, assisted communication, auditory integration training, sensory integration therapy, exercise/physical therapy)
  • Social skills training in some children with autism spectrum disorder, including those with comorbid anxiety disorders; [5] children with autism spectrum disorder and comorbid ADHD may benefit less from social skills training [5]

Pharmacotherapy

No pharmacologic agent is effective in the treatment of the core behavioral manifestations of autistic disorder, but drugs may be effective in treating associated behavioral problems and comorbid disorders (eg, self-injurious behaviors, movement disorders). The possible benefits from pharmacotherapy must be balanced against the likely adverse effects on a case-by-case basis (eg, venlafaxine may increase high-intensity aggression in some adolescents with autism [6] )

Medications used in managing related behavioral problems and comorbid conditions in children with autism include the following:

  • Second-generation antipsychotics (eg, risperidone, aripiprazole, ziprasidone)
  • SSRI antidepressants (eg, fluoxetine, citalopram, escitalopram)
  • Stimulants (eg, methylphenidate)

See Treatment and Medication for more detail.

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Background

Autism is a condition that manifests in early childhood and is characterized by qualitative abnormalities in social interactions, markedly aberrant communication skills, and restricted repetitive and stereotyped behaviors. A heterogeneous group of disorders includes the trait of autism.

Motion anomalies

Motion anomalies are a prominent feature in a subset of individuals and have been reported at birth in some persons with autism. Motion analysis may provide evidence of autism in early infancy, before other manifestations occur. [7]

The motion anomalies demonstrated by children with autism are often highly characteristic and noticeable. An example of a motion typical in autism occurs when the child places a hand with fingers separately outstretched before the eyes and rapidly moves the hand back and forth. A similar experience results from moving up and down while gazing through the slats of Venetian blinds. This action is described as self-stimulation because it produces a visual sensation of movement. (See Presentation.)

Many of the motions of children with autism appear to be attempts to provide themselves with sensory input in a barren environment. Through special education, children may learn to suppress the movements, although these may subsequently be exhibited at times of particular stress or excitement.

Causes

Although the etiology of autism is unknown, hypotheses include genetic abnormalities, obstetric complications, exposure to toxic agents, and prenatal, perinatal, and postnatal infections. [8, 9, 10, 11] Maternal rubella is associated with significantly higher rates of autism and other conditions in children. Additionally, tuberous sclerosis is associated with autism as a comorbid disorder. [12] Approximately 10% of children with a pervasive developmental disorder exhibit a known medical condition. (See Etiology.)

On the other hand, anecdotal reports that autism may be linked with vaccinations (eg, for measles, mumps, and rubella) have not been supported by broader research. [13] Research from the CDC indicates that the number of childhood vaccines administered, either in a single day or during a child's first 2 years, has no effect on the risk of developing an autism spectrum disorder (ASD). According to results of a case-control study of more than 1000 children born between January 1994 and December 1999, exposure to antibody-stimulating proteins or polysaccharides from vaccines between the ages of 3 months and 2 years was not associated with an increased risk of developing an ASD. The study included 256 children with an ASD and 752 healthy controls. [14, 15] Parents should be encouraged to fully immunize their children. [16] (See Etiology.)

Effective treatment of associated behavioral problems includes intensive behavioral, educational, and psychological components. Interventions initiated at the time of diagnosis increase the likelihood of a favorable outcome. [17] Regular screening of infants and toddlers for symptoms and signs of autistic disorder is crucial because it allows for early referral of patients for further evaluation and treatment. (See Treatment.)

The initial clinical descriptions of autism suggested that cold, rejecting parents ("refrigerator mothers") caused autism in offspring; however, careful study of children with autism and their parents has disproved this hypothesis. Autism is not caused by a lack of warmth and affection in parents, nor by any other emotional or psychological parental deficits. Blaming parents for the development of autism in their children is inappropriate.

Diagnosis

Several instruments have been developed to diagnose autism and other pervasive developmental disorders. Administering these tools in a reliable and valid manner requires extensive training and experience. Therefore, unless they have wide experience with children with autism and understand the concepts implicit in the diagnostic criteria and rating scales, pediatricians and other clinicians are advised to refer patients with possible autism to experienced clinicians for definitive diagnostic evaluations. (See the screening checklist below.)

The significance of answers to individual Autism S The significance of answers to individual Autism Screening Checklist items is as follows: Item 1- A "yes" occurs in healthy children and children with some pervasive developmental disorders; a "no" occurs in children with autism, Rett syndrome, and other developmental disorders. Item 2 - A "yes" occurs in healthy children, not children with autism. Item 3 - A "yes" occurs in healthy children and children with Asperger syndrome (ie, high-functioning autism); a "no" occurs in children with Rett syndrome; children with autism may elicit a "yes" or a "no"; some children with autism never speak; some children with autism may develop speech normally and then experience a regression with the loss of speech. Item 4 - A "yes" occurs in healthy children and children with Asperger syndrome and some other pervasive developmental disorders; a "no" occurs in children with developmental disorders; children with autism may elicit a "yes" or a "no." Items 5-10 - Scores of "yes" occur in some children with autism and in children with other disorders. Item 11 – A "yes" occurs in healthy children; a "no" occurs in some children with autism and in children with other disorders. Items 12, 13 - Scores of "yes" occur in some children with autism and in children with other disorders. Items 14-19 - Scores of "yes" occur in children with schizophrenia and other disorders, not in children with autism, Asperger syndrome, or other autism spectrum disorders. The higher the total score for items 5-10, 12, and 13 on the Autism Screening Checklist, the more likely the presence of an autism spectrum disorder.

One goal of this article is to convey fundamental concepts related to autism and related conditions. Readers of this article must obtain considerable additional training before they can reliably and validly apply diagnostic criteria and rating tools.

Treatment

Individualized, intensive behavioral and psychological interventions must be instituted immediately after the diagnosis of autism in order for the patient to achieve an optimal outcome. Although controversy surrounds the appropriate form of special education, some evidence suggests that an individual educational program must be developed by a special educator familiar with autistic disorder and related conditions.

Because deficits in language and communication are often major impediments to progress in educational, work, and personal settings, patients often benefit from specialized communication devices and training. Persons experienced in the needs and treatment of individuals with serious communication handicaps (ie, speech and language specialists) may help the patient to maximize communication skills.

Although psychoanalytic approaches to treatment of children with autism were common in the mid-20th century, these approaches were not found to be effective and are no longer used. Pharmacotherapy is ineffective in treating the core deficits of autism but may be effective in treating associated behavioral problems and comorbid disorders. The possible benefits from pharmacotherapy must be balanced against the likely adverse effects on a case-by-case basis. (See Treatment.)

Practice guidelines

The American Academy of Child and Adolescent Psychiatry's practice guidelines for the assessment and treatment of children and adolescents with ASD include the following recommendations: [18, 19]

  • Questions about core symptoms of ASD should be a routine part of psychiatric and developmental assessments of young children.
  • If screening reveals significant ASD symptomatology, a thorough evaluation should be performed and possible comorbid diagnoses should be considered.
  • Children with ASD should undergo a multidisciplinary assessment, including a physical examination, a hearing screen, communication and psychological tests, and genetic testing.
  • Clinicians should help families obtain educational and behavioral interventions, such as applied behavioral analysis (ABA) programs.
  • Pharmacotherapy should be offered for specific target symptoms or comorbid conditions.
  • Clinicians should maintain an active role in the planning of long-term treatment.
  • Families should be asked about the use of alternative/complementary treatments.
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Pathophysiology

Neural anomalies

In patients with autism, neuroanatomic and neuroimaging studies reveal abnormalities of cellular configurations in several regions of the brain, including the frontal and temporal lobes and the cerebellum. Enlargements of the amygdala and the hippocampus are common in childhood. Markedly more neurons are present in select divisions of the prefrontal cortex of autopsy specimens of some children with autism, compared with those without autism. [20]

Magnetic resonance imaging (MRI) studies have suggested evidence for differences in neuroanatomy and connectivity in people with autism compared with normal controls. Specifically, these studies have found reduced or atypical connectivity in frontal brain regions, as well as thinning of the corpus callosum in children and adults with autism and related conditions.

In a study that included 17 adults with high-functioning autism and 17 age- and IQ-matched control subjects, functional magnetic resonance imaging (fMRI) of the brain that showed neural representations of social interactions was able to accurately identify individuals with autism. Scans were performed as study subjects thought about a set of social interaction verbs from both an action and a recipient perspective. [21, 22]

Importantly, some of the regional differences in neuroanatomy correlate significantly with the severity of specific autistic symptoms. [23, 24] For example, social and language deficits of people with autism likely are related to dysfunction of the frontal and temporal lobes. [25]

In a study of postmortem brain tissue from 11 children with autism and 11 unaffected controls, researchers found focal disruption of cortical laminar architecture in the cortexes of 10 of the children with autism and 1 of the controls, suggesting that brain irregularities in autism may have prenatal origins. The patches of abnormal neurons were found in the frontal and temporal lobes, regions involved in social, emotional, communication, and language functions. Since the changes were in the form of patches, the researchers believe that early treatment could rewire the brain and improve ASD symptoms. [26, 27]

On MRI scans, the brains of children with autism spectrum disorder demonstrate greater myelination in bilateral medial frontal cortices and less myelination in the left temporoparietal junction. [28] Similarly, region-specific differences in the concentrations of gray matter, made up of neuronal cell bodies, dendrites, unmyelinated axons and glial cells, are also found in the brains of people with autism. [29]

Postmortem specimens of the brains of people with autism demonstrated reductions for gamma-aminobutyric acid–B (GABAB) receptors in the cingulate cortex, a key region for the evaluation of social relationships, emotions, and cognition, and in the fusiform gyrus, a crucial region to evaluate faces and facial expressions. [30] These findings provide the basis for further investigation of autism and other pervasive developmental disorders.

Metabolic anomalies

In animal studies, dysfunction of serotonin and the neuropeptides oxytocin and vasopressin has been associated with abnormalities in affiliative behaviors. Neurophysiologic dysfunction involving 1 or more of these substances may also be present in humans with autism.

Elevations of blood serotonin levels occur in approximately one third of individuals with autistic disorder and are also reported in the parents and siblings of patients. Functional anomalies in other neurotransmitters (eg, acetylcholine, glutamate) have also been identified in some people with autism spectrum disorder. [25, 31]

Serum biotinidase is reduced in some people with autistic disorder. This enzyme is required for the use and recycling of the B vitamin biotin. Deficiency of biotin has been linked with behavioral disorders.

Immunologic studies have identified abnormalities such as decreased plasma concentrations of the C4B complement protein. Such abnormalities may be the source of the increased susceptibility to infection seen in some people with autism.

Diet is a controversial aspect of autism. The greatest attention has been given to gluten- and casein-free diets; anecdotal information suggests that these diets help some children with autism. [32] Test findings suggest that low-functioning children with autism may have impairment in the metabolism of phenolic amines. [33] Therefore, symptoms of autistic disorder are possibly aggravated by the consumption of dairy products, chocolates, corn, sugar, apples, and bananas; however, no large population studies have confirmed this.

Oxidative stress may play a role in the pathogenesis and the pathophysiology of autism. [34] Compared with normal children, children with autism have decrements in the following [34] :

  • Plasma levels of cysteine, glutathione, and methionine
  • The ratio of S -adenosyl-L-methionine (SAM) to S -adenosyl-L-homocysteine (SAH)
  • The ratio of reduced to oxidized glutathione

Some children with autism display hyperlacticacidemia [35] as well as evidence of mitochondrial disorders [35] including carnitine deficiency. [36] These abnormalities may reflect disturbed neuronal energy metabolism.

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Etiology

In the 1940s, in his seminal papers that first identified autism, the child psychiatrist Leo Kanner conjectured that infantile autism resulted from rejection of the infant by emotionally cold parents ("refrigerator mothers"). In the 1950s and 1960s, Bruno Bettelheim popularized this idea. Since then, careful family studies have disproved the hypothesis that the development of autistic disorder in children is caused by faulty parenting. Sensitive clinicians communicate to parents that their parenting skills did not cause their child's autism. Repeated communication of this fact will help to minimize the guilt often experienced by parents of autistic children.

The causes of autistic disorder are unknown. Hypotheses include obstetric complications, infection, genetics, and toxic exposures. [37, 38, 39] None of these, however, has been established as a definite etiology.

Obstetric complications

Many individuals with autism and related conditions experienced untoward events in their prenatal and neonatal periods and during delivery. [8, 9, 10, 40] It is unclear whether the obstetric complications caused autistic disorder or whether autism and obstetric complications resulted from environmental or other problems.

In a large Danish study published in JAMA, maternal use of valproate during pregnancy was associated with a significantly increased risk for autism in offspring. The drug is already not recommended for use in pregnant women due to the risk of congenital malformations and its possible association with low intelligence in children exposed during pregnancy.

Researchers used data on all children born in Denmark between 1996 and 2006. Of the 655,615 children born in the study period, 5437 had autism spectrum disorder, including 2067 with childhood autism. There were 2644 children exposed to antiepileptic drugs during pregnancy, 508 of whom were exposed to valproate. Analysis showed that the children exposed to valproate had a 3-fold increased risk for autism spectrum disorder and a 5-fold increased risk for profound childhood autism compared with unexposed children, even after adjustment for parental psychiatric disease and epilepsy. [41, 42]

The management of women with epilepsy who desire to bear children can be challenging. A woman with an ongoing seizure disorder requires treatment because maternal seizures can result in serious morbidity and mortality for the mother and the fetus. To stop anticonvulsant therapy when a woman with a seizure disorder becomes pregnant to avoid teratologic effects may precipitate uncontrolled seizures that may be fatal to the mother and the fetus. Therefore physicians treating women with child-bearing potential can appropriately initiate frank conversations about future pregnancies. Juvenile myoclonic epilepsy and other seizure disorders typically cause seizures throughout adulthood so pharmacotherapy throughout adulthood is a reasonable treatment plan. While valproate is an excellent agent to control a vast spectrum of seizure disorders, its use in women of child-bearing potential is fraught with danger due to the great risk of producing autism spectrum disorders, spina bifida, and other birth defects. A frank conversation between the physician and the woman of child-bearing potential about the risks and benefits of specific antiepileptic drugs for the mother and the fetus is indicated. Documentation of these conversations is the medical record is needed. This record may be useful in court if legal action is initiated if a child has birth defects.

Exposure of the mother to selective serotonin reuptake inhibitors, particularly during the first trimester, may increase the risk that her offspring will develop an autism spectrum disorder. [43]

Severe, early-gestation maternal hypothyroxinemia is associated with an increased risk of having a child with autism, according to a new study that involved 5100 women and 4039 of their children. Severe maternal hypothyroxinemia early in gestation increased the likelihood of having an autistic child by almost 4-fold. By age 6, children of mothers with severe hypothyroxinemia had higher autistic symptom scores on the Pervasive Developmental Problems subscale of the Child Behavior Checklist and the Social Responsiveness Scale. [44, 45]

Infection

An infectious basis for some cases of autistic disorder is suggested by the large number of children with autistic disorder born to women who contracted rubella during pregnancy. This finding supports the hypothesis that this infection triggers a vulnerability to the development of autistic disorder in the fetus.

Familial and genetic factors

Familial factors influence the risk for autism spectrum disorders. The rate of autism spectrum disorder in children born into families that already have a child with an autism spectrum disorder is as high as 18.7 %, and the risk is twice as high in children born to families with 2 or more children with an autism spectrum disorder. [46] Girls born to a family that has a child with an autism spectrum disorder have 2.8 times the risk of having such a disorder. [46]

Twin studies have demonstrated a moderate degree of genetic heritability for autism and autism spectrum disorders, [47, 48, 49] with environment making a substantial contribution to the development of these conditions in the study subjects. [49]

Multiple family studies have suggested genetic components in many cases of autism. [50, 40, 51] For example, some asymptomatic first-degree relatives of some probands with autism have abnormalities in serotonin and other chemicals similar to the probands.

Finding genetic bases for autism is a promising research goal. Factor analysis of datasets from the Autism Genome Project has suggested linkage of a joint attention factor with 11q23 and of a repetitive sensory-motor behavior factor with 19q13. [52] However, the clinical usefulness of the assessment of families of individuals with autism has not been established.

While a third of monozygotic twins are concordant for autism, dizygotic twins are concordant for autism at rates of 4-8%, [53] which is comparable to siblings. A focused neurogenetic evaluation of children with autism spectrum disorder yields a genetic disorder in two fifths of the children. [54] For example, mutations in the gene SHANK3 are associated with autism spectrum disorders. [55]

Fragile X syndrome, a condition associated with autism, can be identified through genetic testing. [56] Antagonists to metabotropic glutamate receptors can reverse the symptoms in mouse models of fragile X syndrome. [57] Autism has also been associated with tuberous sclerosis, a disorder with specific genetic mutations. [58, 59]

Toxic exposure

Exposures to toxins, chemicals, poisons, and other substances have been hypothesized to cause autism. Although anecdotal case reports suggest that such exposures may play a role in isolated cases of autistic disorder, a causative role for toxins in the development of autism in general has not been demonstrated.

Roberts et al [60] and Samson [61] have reported an association between exposure to the organochlorine pesticides dicofol and endosulfan during the first trimester of pregnancy and the subsequent development of autism spectrum disorder in children. Potential mothers can wisely be advised to avoid exposure to organochlorine pesticides.

In parts of the world, exposure to specific toxins may influence local autism rates. For example, the high incidence of autism in areas of Japan has been hypothesized to be due to a toxic effect of certain fish. Although toxins may play a role in the development of isolated cases of autism in Japan, they have not been proved to be generally causative of autism there. Another possible explanation for the high autism rates in Japan is the excellent training of Japanese clinicians; low rates elsewhere may reflect the limited abilities of clinicians to diagnose autism.

Some studies have documented associations between autism and air pollution. One, from North Carolina found a link between exposure to traffic-related air pollution, particularly during the third trimester, to the development of autism in offspring. These results add to the evidence already provided by previous studies conducted in California. [62]

Another study of children living in counties in Pennsylvania found that children with autism were 1.4 to two times more likely to have been exposed to higher levels of air pollution, especially the toxins styrene and chromium, during pregnancy and the first 2 years of life than children without the disorder. [63] Cyanide, methylene chloride, methanol, and arsenic were also linked to increased risk of autism.

Parental age

Meta-analyses of epidemiologic studies have shown that autism risk in offspring increases with advancing age of either parent. Sandin et al reported that, after controlling for paternal age, the adjusted relative risk for autism was 1.52 in the offspring of mothers aged 35 years or older compared with mothers aged 25-29 years. [64] Hultman et al found that, after controlling for maternal age, offspring of men aged 50 years or older were 2.2 times more likely to have autism than offspring of men aged 29 years or younger. [65]

Vaccination

Some children have developed autism after immunizations, including inoculations for measles, mumps, and rubella. However, several population studies have demonstrated no association between childhood immunization and the development of autism and related conditions. [66, 67, 68, 69] } [70] } [71]

Thompson and colleagues detected no causal association between exposure to vaccines that contain thimerosal and neuropsychological deficits at age 7-10 years. [69] In fact, in early 2010, the Lancet retracted the 1998 article by Wakefield et al that originally linked autism with measles-mumps-rubella (MMR) vaccination, citing flaws in the study and 2 claims in it that were "proven to be false." [70]

Parents can permit the recommended childhood immunizations without fear of causing autism and related conditions. Adherence to recommended immunization schedules, including immunization for measles, mumps, and rubella, is highly recommended. [71]

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Epidemiology

Reported rates of autism spectrum disorder have been rising in many countries over the past 2 decades. [72, 73] It remains unclear how much of these data represent an actual increase and how much reflect changes in diagnostic definitions and practices, as well as increasing awareness among the general public and within the medical profession. [74, 75, 76] Further epidemiologic studies are needed.

However, such studies of relatively uncommon conditions such as autism spectrum disorder are expensive. A suitable research strategy is the administration of multiple screenings in a population, each time identifying more likely subjects for detailed investigation.

For example, a reporting tool, such as the Autism Screening Checklist, can be distributed to all parents and guardians in a target population. See the image below.

The significance of answers to individual Autism S The significance of answers to individual Autism Screening Checklist items is as follows: Item 1- A "yes" occurs in healthy children and children with some pervasive developmental disorders; a "no" occurs in children with autism, Rett syndrome, and other developmental disorders. Item 2 - A "yes" occurs in healthy children, not children with autism. Item 3 - A "yes" occurs in healthy children and children with Asperger syndrome (ie, high-functioning autism); a "no" occurs in children with Rett syndrome; children with autism may elicit a "yes" or a "no"; some children with autism never speak; some children with autism may develop speech normally and then experience a regression with the loss of speech. Item 4 - A "yes" occurs in healthy children and children with Asperger syndrome and some other pervasive developmental disorders; a "no" occurs in children with developmental disorders; children with autism may elicit a "yes" or a "no." Items 5-10 - Scores of "yes" occur in some children with autism and in children with other disorders. Item 11 – A "yes" occurs in healthy children; a "no" occurs in some children with autism and in children with other disorders. Items 12, 13 - Scores of "yes" occur in some children with autism and in children with other disorders. Items 14-19 - Scores of "yes" occur in children with schizophrenia and other disorders, not in children with autism, Asperger syndrome, or other autism spectrum disorders. The higher the total score for items 5-10, 12, and 13 on the Autism Screening Checklist, the more likely the presence of an autism spectrum disorder.

The checklist identifies those children with characteristics of an autism spectrum disorder and differentiates them from children with child-onset schizophrenia. (See History).

Occurrence in the United States

Autism spectrum disorder is one of the most common childhood developmental disabilities. Autistic disorder or related conditions were found to affect 14.7 in 1,000 (1 in 68) children aged 8 years living in 11 communities monitored by the US Centers for Disease Control and Prevention (CDC). [77] However, overall prevalence estimates of autistic spectrum disorder varied widely across the 11 monitored communities (range, 5.7-21.9 in 1,000 children aged 8 years).

In its study, the CDC reported a 29% rise in prevalence from 2008 to 2010 in children aged 8 years, or an increase from 11.3 in 1,000 to 14.7 in 1,000 for the 11 sites that provided data for both surveillance years. From 2002 to 2010, an estimated increase of 123% occurred in children aged 8 years. [77] Estimates of the prevalence of autism suggest that as many as 400,000 individuals in the United States have autism or a related condition.

International occurrence

Autistic disorder and related conditions are estimated to affect up to 10-15 people per 10,000 population worldwide. In a population-based study of all 7- to 12-year-old children (N = 55,266) in a South Korean community, Kim et al estimated that the prevalence of autism spectrum disorders was 2.64% [78]

Studies in Japan report much higher rates than are found in other countries. [79] Japanese investigators suggest that these findings reflect the careful evaluations performed by Japanese clinicians, which may identify cases that would be overlooked in other countries. Alternatively, autism may be more common in Japan because of gastrointestinal and other infections transmitted through the ingestion of seafood and other aquatically derived foods that are characteristic of the Japanese diet.

Sex-related demographics

Estimates of the prevalence of autism spectrum disorder vary widely by sex. Combining data from all 11 Autism and Developmental Disabilities Monitoring (ADDM) Network communities, ASD prevalence was 23.7 per 1,000 (one in 42) boys and 5.3 per 1,000 (one in 189) girls (prevalence ratio: 4.5 for all sites combined). The male-to-female ratio ranged from 3.6 (Alabama and Colorado) to 5.1 (North Carolina). [77]

Autistic disorder is most common in boys who have the 46,XY karyotype (ie, the normal male karyotype). In some studies, fragile X is reported in approximately 10% males with autistic disorder. [80, 81, 82, 83, 84, 85]

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Prognosis

The prognosis in patients with autism is highly correlated with their IQ. Low-functioning patients may never live independently; they typically need home or residential care for the rest of their lives. High-functioning patients may live independently, hold jobs successfully, and even marry and have children. Remission of autism has been described in anecdotal case reports.

High-functioning individuals with autistic disorder are similar to people with Asperger syndrome. Please refer to the Medscape Reference article Asperger Syndrome for further information and to learn more about high-functioning autism.

Comorbid disorders

Gastrointestinal disorders, particularly constipation and chronic diarrhea, are more common in children with autism spectrum disorder. The risk of gastrointestinal disorders increases with the severity of autism symptoms. [86]

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Patient Education

Because local boards of education may be ignorant about the needs of children with autistic spectrum disorder and related conditions, pediatricians and parents should seek advice from knowledgeable sources such as the Autism Society of America, which maintains a Web site and offers a toll-free hotline at 1-800-3-AUTISM, providing information and referral services to the public. Legal assistance may be necessary to influence a board of education to fund appropriate education for a child with autistic disorder and related conditions.

People with developmental disabilities, including Asperger syndrome, are vulnerable to sexual abuse, with the most severely disabled being at highest risk. Parents and caregivers need to be aware of this increased risk. Additionally, children with Asperger syndrome must be trained to recognize impending sexual abuse and to develop plans of action to abort it. [87]

Almost half of a sample of more than 1000 children with autism spectrum disorders exhibited elopement, wandering away from home, school, and other safe environments. [88] Parents of children with autism spectrum disorders need to be warned that there is a fair chance that their child, without warning, may walk away from home or school to go to an environment where there is a risk for potential danger. Additionally, parents need to be advised to request that teachers and other caregivers vigilantly watch the child to prevent elopement.

For patient education information, see the Brain and Nervous System Center, as well as Asperger Syndrome.

Obtaining informed consent

People with autism are identified as a highly vulnerable population because of the presence of cognitive, social, and mental impairments. Regulatory agencies have expressed particular concern that the rights of children with autistic disorder and related conditions be carefully protected.

Some have suggested that parents may not be impartial guardians and that third parties be used instead of parents to provide informed consent for clinical and research purposes. However, parents are generally excellent advocates seeking the best for their children. Nevertheless, clinicians must take particular care to ensure that informed consent is obtained in order to prevent misinterpretations and eventual medicolegal problems.

Except in emergencies, patients, parents, guardians, and surrogates must be aware of the diagnostic and treatment possibilities and must provide permission for possible interventions. By making a video recording of the process of explaining to the parent the recommended procedures, in addition to the signing of written release forms, the clinician establishes evidence that he/she imparted appropriate information to the correct party. (See the video below.)

Clinicians are advised to videotape the process of verbally explaining the protocol and answering questions. Permission must be explicitly given to perform the procedure and cannot continue until the parents agree. Parents are asked to give permission to complete this protocol. The entire process is videotaped. In this segment, the mother of a healthy, normal control child gives informed consent to participate as a volunteer in a research study of autism. Occasionally, parents decline to give consent, and the procedure must cease. An earlier version of this videotape is in the New York University Medical Library, New York, New York.

Published resources for parents

Recommended readings for parents include the following:

  • Attwood T. The Complete Guide to Asperger's Syndrome. London, UK: SK Kingsley Publishers; 2006
  • Baron-Cohen S, Howlin P. Teaching Children with Autism to Mind-read: a Practical Guide for Teachers and Parents. New York, NY: Wiley; 1998
  • Cohen S. Targeting Autism. Berkeley, CA: University of California Press; 1998
  • Gaus VL. Cognitive/Behavioural Therapy for Adult Asperger's Syndrome. New York, NY: The Guilford Press; 2007
  • Hart CA. A Parent's Guide to Autism. New York, NY: Pocket Books; 1993
  • Hollander E. Autism Spectrum Disorders. Volume 24 of the Medical Psychiatry Series. New York, NY: Marcel Dekker; 2003
  • Lovaas I. The Autistic Child: Language Development through Behavior Modification. New York, NY: Irvington Press; 1977
  • Matthews P, Matthews T. (2012) Charter of Rights for People with Autism: “Reflections” and Personal Experiences. Dublin, Ireland: Original writing; 2012
  • Offit PA. Autism's false prophets. New York, NY: Columbia University Press; 2008
  • Powers M. Children with Autism: A Parents' Guide. Bethesda, Md: Woodbine House; 2000
  • Quill K. Teaching Children with Autism: Strategies to Enhance Communication and Socialization. Albany, NY: Delmar Publishers; 1995
  • Wing L. The Autistic Spectrum: A Parent's Guide to Understanding and Helping Your Child. London, England: Ulysses Press; 2001

Additional resources

Individuals with autism and related conditions, as well as their advocates, can benefit from the experiences of other individuals and advocates who are dealing with autism. (See the organizations and resources listed below.)

Autism Society of America

7910 Woodmont Ave, Suite 650

Bethesda, MD 20814-3015

Phone: 1-800-328-8476

Autism Society of America

Manhattan Chapter

25 West 17th St Ground Floor

New York, NY 10011

Autism Society of Canada

2-20 College St

Toronto, Ontario

Canada M5G 1K2

National Alliance for Autism Research

Research Park

414 Wall St

Princeton, NJ 08540

Phone: 888-777-NAAR

The National Autistic Society

393 City Rd

London EC1V 1NG

United Kingdom

Phone: +44 (0)20 7833 2299

National Institutes of Health

http://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-pervasive-developmental-disorders/index.shtml

Asperger Syndrome Coalition of the United States (ASC-US) Inc

PO Box 49267

Jacksonville FL 32240-9267

LADDERS

65 Walnut St

Wellesley MA 02481

Phone: 781-449-6074

Autism Research Institute

4182 Adams Ave

San Diego, CA 92116

Fax: 619-563-6840

Autism Speaks

5455 Wilshire Blvd, Suite 715

Los Angeles, CA 90036

Phone: 323-549-0500

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