Asperger syndrome

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

Autism Spectrum Disorder (ASD) is a category of neurodevelopmental disorders with problems in social communication/interaction and restricted and repetitive behaviors/interests. According to the Diagnostic And Statistical Manual Of Mental Disorders, Fifth Edition (DSM-5) released by the American Psychiatric Association (APA) in 2013, Asperger Syndrome (AS) goes under a spectrum of disorders called ‘Autism Spectrum Disorder (ASD)’.^[1] Asperger Syndrome is named after Hans Asperger, an Austrian physician. He was the first to describe and separate Asperger Syndrome from autism and called it ‘autistic psychopathy’ which later became known as Asperger Syndrome.

Asperger Syndrome (AS) is believed to be first described as ‘autistic psychopathy’ in German by Hans Asperger.^[2][3] He distinguished his cases from autism which later became known as ‘Asperger’s Syndrome’.^[4] In 1981, Lorna Wing published Asperger’s works in English.^[5] In 1994, DSM-4 classified Asperger Syndrome (AS) as a subtype in the category of pervasive developmental disorders (PDD). In 2013, DSM-5 combined 4 of the 5 subtypes of pervasive developmental disorders (PDD) under the Autism Spectrum Disorder (ASD) category.^[6]

According to the Diagnostic And Statistical Manual Of Mental Disorders, Fifth Edition (DSM-5) released by the American Psychiatric Association (APA) in 2013, Asperger Syndrome (AS) is in the Autism Spectrum Disorder (ASD) category.^[1] Autism Spectrum Disorder (ASD) is a category of neurodevelopmental disorders in DSM-5 with problems in social communication/interaction, restricted and repetitive behaviors/interests.

The exact pathophysiology of Asperger Syndrome is unknown, however some neuroimaging and neuropsychological studies have reported some findings.^[7][8]

The exact cause of Asperger (AS) is unknown. Many factors including genetics, family history of autism spectrum disorders (ASD) and enviornmental factors such as older parental age, prematurity, low birth weight and pregnancy complications have been associated with autism spectrum disorder (ASD).^{[9][10][11][12][13][14][15]}

Prevalence rates for Asperger Syndrome ranges from 0.03 to 4.84 per 1,000 in different studies.^[2] In 2014, the overall prevalence of autism spectrum disorders (ASD) was estimated to be 16.8 per 1,000 children aged 8 years.^[16] The male to female prevalence ratio for ASD is approximately 4 to 1.^[16] The estimate for ASD prevalence was 7% and 22% higher among white children compared to black and Hispanic children respectively.^[16]

Several risk factors associated with Asperger Syndrome (AS) and austim spectrum disorder (ASD) are: male gender, older parental age, family history of austim spectrum disorder (ASD), prematurity, low birth weight and pregnancy complications.^{[16][12][11][10][17][15]}

Screening instruments for Asperger Syndrome include: Autism Screening Questionnaire (ASQ), Autism Spectrum Quotient (AQ), Autism Spectrum Screening uestionnaire (ASSQ) and diagnostic instruments for Asperger Syndrome include: Asperger Syndrome Diagnostic Scale (ASDS), Gilliam Asperger’s Disorder Scale (GADS) and Asperger Syndrome (and high-functioning autism) Diagnostic Interview (ASDI).^[8]

It is believed that 20% of Asperger Syndrome patients ‘grow out’ of their disorder and and do not meet the diagnostic criteria as adults, whereas many other patients improve.^[18] Diagnosis of AS is often delayed and sometimes done in adulthood.^[19] Social impairment is lifelong.^[20] Early diagnosis and intervention in patients with AS may improve adaptation and adjustment of the child.^[19] Asperger Syndrome (AS) is associated with several conditions such as attention deficit hyperactivity disorder (ADHD) (most common in pediatric patients)^[21], depression (most common in adolescent and adult patients)^[21][22] and anxiety disorders.^[22]

The Diagnostic Criteria for Autism Spectrum Disorder (ASD) released by the American Psychiatric Association’s Diagnostic and Statistical Manual, Fifth Edition (DSM-5) is used for the diagnosis of Asperger Syndrome (AS).^[1]

Several symptoms may be seen in Asperger Syndrome (AS) with impairments in social interaction, communication and restricted, repetitive behaviors and interests being the most important. There may be impairments in motor and sensory functions, speech, language and.sleep.

The most common clinical signs in Asperger Syndrome (AS) are impairments in social communication and repetitive behaviors.

Routine laboratory testing is not recommended.^[23]

Routine neuroimaging, electroencephalography (EEG) and genetic testing are not recommended in patients with Asperger Syndrome (AS).^[24][23]

Medical treatments used in Asperger Syndrome include: stimulants, a-2 adrenergic agonists, atypical antipsychotics, antidepressants and anticonvulsants. Many studies believe that medications alone can not improve Asperger Syndrome’s (AS) symptoms and other complementary interventions (social and behavioral) are required.^[25]

Behavioral therapies in Asperger Syndrome (AS) are used to help the patients with their social communication and to develop social skills.^[8]

Based on a prevalence of 1.1 % for autism spectrum disorder (ASD) in the US, the economic burden for ASD has been estimated to be $268.2991 billion (1.467% of GDP) and $460.8002 billion (1.649% of GDP) in 2015 and 2025 respectively.^[26]

There have been some experimental therapy and suggestions such as oxytocin and treatment with stem cells in patients with Asperger Syndrome (AS).^[25]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

Asperger Syndrome (AS) is believed to be first described as ‘autistic psychopathy’ in German by Hans Asperger.^[1][2] He distinguished his cases from autism which later became known as ‘Asperger’s Syndrome’.^[3] In 1981, Lorna Wing published Asperger’s works in English.^[4] In 1994, DSM-4 classified Asperger Syndrome (AS) as a subtype in the category of pervasive developmental disorders (PDD). In 2013, DSM-5 combined 4 of the 5 subtypes of pervasive developmental disorders (PDD) under the Autism Spectrum Disorder (ASD) category.^[5]

• In 1938, Hans Asperger described ‘autistic psychopaths’ in German.^[1]
• In 1943, Leo Kanner described 11 cases with ‘infantile autism’ in his paper.^[6]
• In 1944, Hans Asperger, described four children with ‘autistic psychopathy’ in his thesis.^[2]
• Asperger used the term ‘autistic psychopathy’ to describe the cases in his studies and distinguished them from autism, which later were became known as ‘Asperger’s Syndrome’.^[3] 
• In 1981, Lorna Wing published Asperger’s works in English (translated from German).^[4]
• In 1991, Uta Frith translated Asperger’s thesis into English. Frith, Uta (1991). Autism and Asperger syndrome. Cambridge New York: Cambridge University Press. ISBN 978-0521386081.
• In 1994, DSM-4 classified Asperger Syndrome (AS) as a subtype in the category of pervasive developmental disorders (PDD).
• In 2013, DSM-5 combined 4 of the 5 subtypes of pervasive developmental disorders (PDD) under the Autism Spectrum Disorder (ASD) category.^[5]

Template:Pervasive developmental disorders

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

According to the Diagnostic And Statistical Manual Of Mental Disorders, Fifth Edition (DSM-5)^[1] released by the American Psychiatric Association (APA) in 2013, Asperger Syndrome (AS) is in the Autism Spectrum Disorder (ASD) category. Autism Spectrum Disorder (ASD) is a category of neurodevelopmental disorders in DSM-5 with problems in social communication/interaction, restricted and repetitive behaviors/interests.

According to the Diagnostic And Statistical Manual Of Mental Disorders, Fifth Edition (DSM-5)^[1] released by the American Psychiatric Association (APA) in 2013, Asperger Syndrome (AS) is in the Autism Spectrum Disorder (ASD) category. Autism Spectrum Disorder (ASD) is a category of neurodevelopmental disorders in DSM-5 with problems in social communication/interaction, restricted and repetitive behaviors/interests.

In DSM-IV, Asperger Syndrome (AS) was one of the 5 subtypes of Pervasive Developmental Disorder (PDD) category (which included: autistic disorder, Asperger’s disorder, childhood disintegrative disorder, pervasive developmental disorder not otherwise specified (PDD-NOS), and Rett syndrome). In 2013, in DSM-5, a category called Autism Spectrum Disorder (ASD) was created by combining 4 of the 5 subtypes of DSM-IV’s Pervasive Developmental Disorder (PDD) category (autistic disorder, Asperger’s disorder, pervasive developmental disorder not otherwise specified (PDD-NOS) and childhood disintegrative disorder).^[1][2]

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

The exact pathophysiology of Asperger Syndrome is unknown, however some neuroimaging and neuropsychological studies have reported some findings.^[1][2]

Neuroimaging studies have shown structural and functional brain abnormalities in patients with Asperger (AS) such as:^[1][2]

• There has been a report on developmental problems of neuronal migration in the cerebral cortex during pregnancy and fetal development in patients with AS which may result in problems in the connectivity of the brain cortex.^[3]
• Smaller gray matter in the ventromedial aspect of the temporal lobe^[4] and bilateral caudate and left thalamus ^[5].
• Greater white matter around the basal ganglia and left inferior parietal lobe, but lower white matter volume in the right corpus callosum.^[6]
• Larger amygdala and hippocampal in patients with AS is associated to their difficulty with emotional reactivity^[7]
• Smaller anterior cingulate cortex (ACC) in AS patients is associated with their difficulty with self monitoring of behavior.^[7]
• Lesion in the white matter of the right middle temporal gyrus.^[8]
• Lower fractional anisotropy (FA) is seen mostly bilaterally and in the white matter (internal capsule, frontal, temporal, parietal and occipital lobe, cingulum and corpus callosum).^[9]
• Localized disconnection in cerebellar neural pathways may lead to abnormalities in adaptive social behavior.^[10]
• Abnormal functional connectivity of medial temporal lobe structures (amygdala and parahippocampus gyrus) is associated with difficulty in social cognition in AS patients.^[11]
• Abnormal dysactivation of the frontal lobe (during neuropsychological tests).^{[12][13][14][15]}
• Abnormal activation in the temporal cortex during face discrimination.^[16]
• Decreased activation of fusiform and extrastriate cortices during facial emotion processing.^[17]
• Executive dysfunctions are associated with abnormality in neural connectivity of the brain cortex.^[18]
• Neuroimaging patterns of AS patients were the same in static stimuli (photo of a face) and dynamic stimuli (real face).^[19]

Some chemical markers associated with AS include:^[1]

• Increase in N-acetyl aspartate/choline (NAA/Cho) level in the right anterior cingulate is associated with higher scores in obsessive compulsive scale in patients with AS.^[20]
• Increased in the activity of the presynaptic dopamine system in the striatum and frontal cortex in patients with AS.^[21]
• There is an association in cortical serotonin 5-HT2A receptor binding and social communication in patients with AS.^[22]
• Administration of oxytocin may improve emotion recognition, affective speech comprehension, increase eye gaze, and social interaction in patients with AS.^[23]

Neuropsychological abnormalities in AS are:^[2]

• Difficulty in passing theory of mind tasks
• Executive dysfunction
• Tendency to interpret visual stimuli in parts rather than wholes (poor central coherence)
• There are studies that suggest in patients with AS there is a Verbal IQ (VIQ) > Poor Performance IQ (PIQ) profile which shows strength on verbal skills relative to visuospatial skills and non-verbal problem solving (nonverbal learning disability)^[24]

Asperger Syndrome (AS) is associated with several conditions which include:

• Attention deficit hyperactivity disorder (ADHD) (most common in pediatric patients)^[25]
• Depression (most common in adolescent and adult patients)^[25][26]
• Bipolar disorder^[25][26]
• Tourette syndrome^[25]
• Obsessive compulsive disorder (OCD)^[25][26]
• Tic disorder^[25]
• Anxiety disorders^[26]
• Schizophrenia^[27] 
• Non-verbal learning disability^[28]
• Difficulty in falling asleep, sleepiness after awakening and during daytime and poor sleep quality^[29]
• There have been case-reports of Asperger Syndrome (AS) associated with aminoaciduria,^[30] ligamentous laxity^[31] and recurrent hypersomnia^[32].

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

The exact cause of Asperger (AS) is unknown. Many factors including genetics, family history of autism spectrum disorders (ASD) and enviornmental factors such as older parental age, prematurity, low birth weight and pregnancy complications have been associated with autism spectrum disorder (ASD).^{[1][2][3][4][5][6][7]}

• Linkage at 1q21-22^[1]
• Linkage at 13q31-33^[1]
• Linkage at 3p14–24^[1]
• Linkage at 3q21–24^[6]
• 17p breakpoints in t(13;17) and t(17;19)^[5]
• 3p22.1p21.31 microdeletion^[8]

Several studies suggest that a familial history of autism spectrum disorder (ASD) is a risk factor for Asperger Syndrome (AS).^[4][3][2]

Several environmental risk factors are associated with autism spectrum disorder (ASD) which include:^[7]

• Advanced maternal age
• Advanced paternal age
• Low birth weight
• Prematurity
• Hyperbilirubinemia, neonatal jaundice
• Maternal immigrant status  
• Pregnancy complications such as eclampsia and pregnancy-induced hypertension
• Air pollutants (traffic-related)
  

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

There are several differential diagnosis to consider in the diagnosis of Asperger Syndrome (AS) including attention deficit–hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), schizophrenia, schizoid personality disorder, schizotypal personality disorder and mood disorders.^[1][2]

• Conditions that must be considered in a differential diagnosis include:^[1][2]
  • Autism spectrum disorder (ASD)
  • Attention deficit–hyperactivity disorder (ADHD)
  • Obsessive compulsive disorder (OCD)
  • Schizophrenia
  • Schizophrenia simplex
  • Residual schizophrenia
  • Schizoid personality disorder
  • Schizotypal personality disorder
  • Semantic pragmatic disorder
  • Nonverbal learning disorder
  • Mood disorders (depression and anxiety)
  • Stereotypic movement disorder
  • Alexithymia
  • Avoidant personality disorder
  • Antisocial personality disorder
  • Borderline personality disorder
  • Narcissistic personality disorder
  • Nonverbal learning disorder
  • Post traumatic stress disorder (PTSD)
  • Social phobia
  • Compulsive (anankastic) personality disorder

• The following table shows the overlap of some differential diagnoses of AS that have abnormal social interaction:^[1]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

Prevalence rates for Asperger Syndrome ranges from 0.03 to 4.84 per 1,000 in different studies.^[1] In 2014, the overall prevalence of autism spectrum disorders (ASD) was estimated to be 16.8 per 1,000 children aged 8 years.^[2] The male to female prevalence ratio for ASD is approximately 4 to 1.^[2] The estimate for ASD prevalence was 7% and 22% higher among white children compared to black and Hispanic children respectively.^[2]

• Prevalence rates for Asperger Syndrome ranges from 0.03 to 4.84 per 1,000 in different studies.^[1]
• In 2014, the overall prevalence of autism spectrum disorders (ASD) was estimated to be 16.8 per 1,000 children aged 8 years.^[2]

• Males are more commonly affected by autism spectrum disorders (ASD) than females.^[2]
• The male to female ratio for ASD is approximately 4 to 1.^[2]

• In 2014, the estimate for ASD prevalence was 7% higher among white children compared to black children.^[2]
• In 2014, the estimate for ASD prevalence was 22% higher among white children compared to Hispanic children.^[2]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

Several risk factors associated with Asperger Syndrome (AS) and austim spectrum disorder (ASD) are: male gender, older parental age, family history of austim spectrum disorder (ASD), prematurity, low birth weight and pregnancy complications.^{[1][2][3][4][5][6]}

Several risk factors have been associated with Asperger Syndrome:

• Male gender: The male to female ratio for austim spectrum disorder (ASD) is approximately 4 to 1.^[1]
• Family history of austim spectrum disorder (ASD)^[2][3][4]
• Race: AS has been reported to be 7% and 22% higher among white children compared to black and Hispanic children.^[5]
• Other risk factors associated with austim spectrum disorder (ASD) include:^[6]
  • Advanced maternal age
  • Advanced paternal age
  • Low birth weight
  • Prematurity
  • Hyperbilirubinemia, neonatal jaundice
  • Maternal immigrant status  
  • Pregnancy complications such as eclampsia and pregnancy-induced hypertension
  • Air pollutants (traffic-related)
    

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

Screening instruments for Asperger Syndrome include: Autism Screening Questionnaire (ASQ), Autism Spectrum Quotient (AQ), Autism Spectrum Screening uestionnaire (ASSQ) and diagnostic instruments for Asperger Syndrome include: Asperger Syndrome Diagnostic Scale (ASDS), Gilliam Asperger’s Disorder Scale (GADS) and Asperger Syndrome (and high-functioning autism) Diagnostic Interview (ASDI).^[1]

• Early diagnosis and intervention in patients with AS may improve adaptation and adjustment of the child.^[2]
• Screening for associated disorders is an important prognostic factor.^[2]
• Screening instruments for Asperger Syndrome include:^[1]
  • Autism Screening Questionnaire (ASQ)
  • Autism Spectrum Quotient (AQ)
  • Autism Spectrum Screening Questionnaire (ASSQ)
• Diagnostic instruments for Asperger Syndrome include:^[1]
  • Asperger Syndrome Diagnostic Scale (ASDS)
  • Gilliam Asperger’s Disorder Scale (GADS)
  • Asperger Syndrome (and high-functioning autism) Diagnostic Interview (ASDI)  

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shakiba Hassanzadeh, MD[2]

It is believed that 20% of Asperger Syndrome patients ‘grow out’ of their disorder and and do not meet the diagnostic criteria as adults, whereas many other patients improve.^[1] Diagnosis of AS is often delayed and sometimes done in adulthood.^[2] Social impairment is lifelong.^[3] Early diagnosis and intervention in patients with AS may improve adaptation and adjustment of the child.^[2] Asperger Syndrome (AS) is associated with several conditions such as attention deficit hyperactivity disorder (ADHD) (most common in pediatric patients)^[4], depression (most common in adolescent and adult patients)^[4][5] and anxiety disorders^[5].

• It is believed that 20% of Asperger Syndrome patients ‘grow out’ of their disorder and and do not meet the diagnostic criteria as adults, whereas many other patients improve.^[1]  
• Diagnosis of AS is often delayed and sometimes done in adulthood.^[2]
• Social impairment is lifelong.^[3]
• Most attend regular education classes with additional support services.^[3]
• Some need special education services because of their social and behavioral impairments.^[3]
• Early diagnosis and intervention in patients with AS may improve adaptation and adjustment of the child.^[2].
• Screening for associated disorders is an important prognostic factor.^[2]

Asperger Syndrome (AS) is associated with several conditions which include:

• Attention deficit hyperactivity disorder (ADHD) (most common in pediatric patients)^[4]
• Depression (most common in adolescent and adult patients)^[4][5]
• Bipolar disorder^[4][5]
• Tourette Syndrome^[4]
• Obsessive compulsive disorder (OCD)^[4][5]
• Tic disorder^[4]
• Anxiety disorders^[5]
• Schizophrenia^[6] 
• Nonverbal learning disability^[7]
• Difficulty in falling asleep, sleepiness after awakening and during daytime and poor sleep quality^[8]
• There have been case-reports of Asperger Syndrome (AS) associated with aminoaciduria,^[9] ligamentous laxity^[10] and recurrent hypersomnia^[11].

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Several factors complicate the diagnosis of Asperger syndrome (AS), an autism spectrum disorder (ASD). Like other ASD forms, Asperger syndrome is characterized by impairment in social interaction accompanied by restricted and repetitive interests and behavior; it differs from the other ASDs by having no general delay in language or cognitive development. Problems in diagnosis include disagreement among diagnostic criteria, controversy over the distinction between AS and other ASD forms or even whether AS exists as a separate syndrome, and over- and under-diagnosis for non-technical reasons. As with other ASD forms, early diagnosis is important, and differential diagnosis must consider several other conditions.

Asperger’s Disorder is defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) by six main criteria:

1. qualitative impairment in social interaction
2. restricted, repetitive and stereotyped behaviors and interests
3. significant impairment in important areas of functioning
4. no significant delay in language development
5. no significant delay in cognitive development, self-help skills or adaptive behaviors (other than social interaction)
6. criteria are not met for another specific pervasive developmental disorder or schizophrenia.^[1]

The World Health Organization ICD-10 criteria are almost identical to DSM-IV:^[2] ICD-10 adds the statement that motor clumsiness is usual (although not necessarily a diagnostic feature); ICD-10 adds the statement that isolated special skills, often related to abnormal preoccupations, are common but are not required for diagnosis; and the DSM-IV requirement for clinically significant impairment in social, occupational, or other important areas of functioning is not included in ICD-10.^[3][4]

The diagnoses of AS or high-functioning autism (HFA) are sometimes used interchangeably; the same child can receive different diagnoses depending on the screening tool.^[5] Diagnoses may be influenced by non-technical issues, such as availability of government benefits for one condition but not the other.^[6] Advocacy and parent support organizations have proliferated around the concept of AS, and there are indications that this has resulted in more frequent diagnoses of AS, which may be given as a “residual diagnosis” to children of normal intelligence who do not meet diagnostic criteria for autism but have some social difficulties.^[7] Underdiagnosis and overdiagnosis are problems in marginal cases; 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.^[8]

Developmental screening during a routine check-up by a general practitioner or pediatrician may identify signs that warrant further investigation. This will require a comprehensive team evaluation to either confirm or exclude a diagnosis of AS. This team usually includes a psychologist, neurologist, psychiatrist, speech and language pathologist, occupational therapist and other professionals with expertise in diagnosing children with AS.^[5][4] Observation occurs across multiple settings; the social disability in AS may be more evident during periods when social expectations are unclear and children are free of adult direction.^[9] A comprehensive evaluation includes neurological and genetic assessment, with in-depth cognitive and language testing to establish IQ and evaluate psychomotor function, verbal and nonverbal strengths and weaknesses, style of learning, and skills for independent living. An assessment of communication strengths and weaknesses includes the evaluation of nonverbal forms of communication (gaze and gestures); the use of non-literal language (metaphor, irony, absurdities and humor); patterns of speech inflection, stress and volume; pragmatics (turn-taking and sensitivity to verbal cues); and the content, clarity and coherence of conversation.^[5] Testing may include an audiological referral to exclude hearing impairment. The determination of whether there is a family history of autism spectrum conditions is important.^[10] A medical practitioner will diagnose on the basis of the test results and the child’s developmental history and current symptoms.^[5] Because multiple domains of functioning are involved, a multidisciplinary team approach is critical;^[2] an accurate assessment of the individual’s strengths and weaknesses is more useful than a diagnostic label.^[9] Delayed or mistaken diagnosis is a serious problem that can be traumatic for individuals and families; diagnosis based solely on a neurological, speech and language, or educational attainment may yield only a partial diagnosis.^[2]

Advances in genetic technology allow clinical geneticists to link an estimated 40% of ASD cases to genetic causes; in one study the diagnostic yield for AS, PDD-NOS and atypical autism was similar to that for classic autism.^[11] Genetic diagnosis is relatively expensive,^[11] and genetic screening is generally impractical. As genetic tests are developed several ethical, legal, and social issues will emerge. Commercial availability of tests may precede adequate understanding of how to use test results, given the complexity of the genetics.^[12]

Parents of children with AS can typically trace differences in their children’s development to as early as 30 months of age, although diagnosis is not made on average until the age of 11.^[10] By definition, children with AS develop language and self-help skills on schedule, so early signs may not be apparent and the condition may not be diagnosed until later childhood. Impairment in social interaction is sometimes not in evidence until a child attains an age at which these behaviors become important; social disabilities are often first noticed when children encounter peers in daycare or preschool.^[9] Diagnosis is most commonly made between the ages of four and eleven, and one study suggests that diagnosis cannot be rendered reliably before age four.^[9]

Asperger syndrome can be misdiagnosed as a number of other conditions, leading to medications that are unnecessary or even worsen behavior; the condition may be at the root of treatment-resistant mental illness in adults. Diagnostic confusion burdens individuals and families and may cause them to seek unhelpful therapies. Conditions that must be considered in a differential diagnosis include other pervasive developmental disorders (autism, PDD-NOS, childhood disintegrative disorder, Rett disorder), schizophrenia spectrum disorders (schizophrenia, schizotypal disorder, schizoid personality disorder), attention-deficit hyperactivity disorder, obsessive compulsive disorder, depression, semantic pragmatic disorder, multiple complex developmental disorder and nonverbal learning disorder.^[2] Differentiating between AS and other ASDs relies on the judgment of experienced clinicians.^[9] Tourette syndrome (TS) should also be considered in differential diagnosis: “It is in nonretarded, rigid individuals on the autistic spectrum, especially those with so-called Asperger syndrome, that differences with less severely affected individuals with TS and OCD may become blurred, or that both disorders may coexist.”^[13] Other problems to be considered in the differential diagnosis include selective mutism, stereotypic movement disorder and bipolar disorder^[10] as well as traumatic brain injury or birth trauma, conduct disorder, Cornelia De Lange syndrome, fetal alcohol syndrome, fragile X syndrome, dyslexia, Fahr syndrome, hyperlexia, leukodystrophy, multiple sclerosis and Triple X syndrome.^[14]

The diagnosis of AS is complicated by the use of several different screening instruments.^[5][15] In addition to the DSM-IV and the ICD-10 criteria, other sets of diagnostic criteria for AS are the Szatmari et al. criteria^[16] and the Gillberg and Gillberg criteria.^[17]

Compared with the DSM-IV and ICD-10 criteria, the requirements of normal early language and cognitive development are not mentioned by Szatmari et al., whereas speech delay is allowed in the Gillberg and Gillberg criteria. Szatmari et al. emphasize solitariness, and both Gillberg and Szatmari include “odd speech” and “language” in their criteria. Although Szatmari does not mention stereotyped behaviors, one of four described stereotyped functions is required by DSM-IV and ICD-10, and two are required by Gillberg and Gillberg. Abnormal responses to sensory stimuli are not mentioned in any diagnostic scheme, although they have been associated with AS.^[3] Because DSM-IV and ICD-10 exclude speech and language difficulties, these definitions exclude some of the original cases described by Hans Asperger. According to one researcher, the majority of individuals with AS do have speech and language abnormalities, and the recent DSM–IV says that “the occurrence of ‘no clinically significant delays in language does not imply that individuals with Asperger Disorder have no problems with communication’ (American Psychiatric Association, 2000, p. 80)”.^[2] The Gillberg and Gillberg criteria are considered closest to Asperger’s original description of the syndrome;^[2] the aggression and abnormal prosody that other authors say defined Asperger’s patients are not mentioned in any criteria.^[4][9][18]

The DSM-IV and ICD-10 diagnostic criteria have been criticized for being too broad and inadequate for assessing adults,^[19] overly narrow (particularly in relation to Hans Asperger’s original description of individuals with AS),^[20][2] and vague;^[15] results of a large study in 2007 comparing the four sets of criteria point to a “huge need to reconsider the diagnostic criteria of AS”.^[3] The study found complete overlap across all sets of diagnostic criteria in the impairment of social interaction with the exception of four cases not diagnosed by the Szatmari et al. criteria because of its emphasis on social solitariness. Lack of overlap was strongest in the language delay and odd speech requirements of the Gillberg and the Szatmari requirements relative to DSM-IV and ICD-10, and in the differing requirements regarding general delays.^[3] A small 2008 study of children referred with a tentative diagnosis of AS found poor agreement among the four sets of criteria, with one overlap being only 39%.^[21] In 2007 Szatmari et al. suggested a new classification system of ASD based on familial traits found by genetic epidemiology.^[22]

Although individuals with Asperger’s tend to perform better cognitively than those with autism, the extent of the overlap between Asperger’s and high-functioning autism is unclear.^[7][23] Overall, relatively few differences are reported between Asperger’s and autism on parameters related to causation. A standard assumption is that Asperger’s and autism have a common cause, and are variable expressions of the same underlying disorder.^[24] A 2008 review of classification studies found that results largely did not support differences between the diagnoses, and that the most salient group characteristics came from IQ characterizations.^[23]

A neuropsychological profile has been proposed for AS;^[25] if verified, it could differentiate between AS and HFA and aid in differential diagnosis. Relative to HFA, people with AS have deficits in nonverbal skills such as visual-spatial problem solving and visual-motor coordination,^[26] along with stronger verbal abilities.^[27] Several studies have found AS with a neuropsychologic profile of assets and deficits consistent with a nonverbal learning disability, but several other studies have failed to replicate this.^[26] The literature review did not reveal consistent findings of “nonverbal weaknesses or increased spatial or motor problems relative to individuals with HFA”, leading some researchers to argue that increased cognitive ability is evidenced in AS relative to HFA regardless of differences in verbal and nonverbal ability.^[28]

• Johnson CP, Myers SM, Council on Children with Disabilities (2007). “Identification and evaluation of children with autism spectrum disorders”. Pediatrics. 120 (5): 1183–215. doi:10.1542/peds.2007-2361. PMID 17967920. Lay summary – AAP (2007-10-29).CS1 maint: Multiple names: authors list (link)

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