We searched Medline, Psychinfo, and Cochrane Library databases from January, 1998, to December, 2008, with the search terms “autism”, “autistic disorder”, “pervasive developmental disorder”, “autism spectrum disorder”, and “Asperger syndrome” in combination with “evaluation”, “diagnosis”, “treatment”, “therapy”, “medication”, “pharmacotherapy”, “epidemiology”, “genetics”, “neuroimaging”, “behavior therapy”, “early identification”, “outcome”, and “complementary and alternative therapy.” We
SeminarAutism
Introduction
Autism is a neurodevelopmental disorder in the category of pervasive developmental disorders, and is characterised by severe and pervasive impairment in reciprocal socialisation, qualitative impairment in communication, and repetitive or unusual behaviour. The Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV)1 and the International Classification of Diseases, 10th edition (ICD-10),2 include autistic disorder, Asperger's syndrome, pervasive developmental disorder-not otherwise specified (PDD-NOS), Rett's syndrome, and childhood disintegrative disorder as pervasive developmental disorders. Clinicians and researchers use autism spectrum disorders to include autism, Asperger's syndrome, and PDD-NOS, which we discuss in this Seminar. For children with Rett's disorder or childhood disintegrative disorder, their clinical course, pathophysiology, and the diagnostic strategies used are different and are not addressed in this Seminar.
Section snippets
Epidemiology
We focus on prevalence of autism spectrum disorders and possible causes of changes in prevalence. Although estimates vary, prevalence seems to have increased greatly since the 1960s, when rates included only autistic disorder. In the 20 years since, in the USA and Europe prevalence rates ranged from five to 72 cases per 10 000 children.3, 4 These estimates were affected by screening, case-confirmation strategies, and sample size, with small sample sizes resulting in high estimates. Prevalence
Clinical characteristics and screening
Core symptoms of autism spectrum disorders affect domains of socialisation, communication, and behaviour (panel 1). Clinical signs are usually present by age 3 years, but typical language development might delay identification of symptoms. Results of prospective studies11 of infants at risk (ie, younger siblings of affected children) have shown that deficits in social responsiveness, communication, and play can be present in those as young as age 6–12 months. Diagnoses show heterogeneity of
Assessment
Children identified to be at risk should be referred for comprehensive developmental and diagnostic assessment for autism spectrum disorders. This assessment might be done through community resources (eg, early intervention staff, educators, psychologists, or speech pathologists), educational agencies, or local developmental clinicians. Reviews of early identification and screening are available.15, 17, 19 If concerns that a child has autism spectrum disorder are validated, comprehensive
Neurobiology
Attempts to identify unified theories explaining core and comorbid deficits have been unsuccessful, which is not surprising in view of the heterogeneous expression of autism spectrum disorders. In studies64 of this disorder as a neurodevelopmental disorder of prenatal and postnatal brain development, researchers have attempted to elucidate these theories by examination of brain growth, functional neural networks, neuropathology, electrophysiology, and neurochemistry. Neurocognitive theories
Causes
Autism spectrum disorder is highly genetic. The relative risk of a second child having this diagnosis is 20–50 times higher than the population base rate,71 and thus families should consider genetic counselling. Parents and siblings often show mild, subsyndromal manifestations of autism, the broad autism phenotype,72 including delayed language, difficulties with social aspects of language (pragmatics), delayed social development, absence of close friendships, and a perfectionistic or rigid
Genetics
Since 2003,12 fundamental changes in our understanding of the genetics of autism have taken place. Previously, this specialty was guided almost exclusively by the common disorder–common gene model,76 proposing that many genes frequently identified in the general population each confer small-to-moderate effects on the phenotype. Only a few common variants have been identified as possible candidate genes in linkage and association studies,77 and many of these have not been verified in subsequent
New developments
Advances in cognitive and affective developmental neuroscience, neurobiology, and the genetics of autism spectrum disorder have resulted in potentially novel methods for early detection and improved targeting and effectiveness of treatments.85 For example, neuroimaging strategies such as functional MRI and magnetoencephalography might provide biomarkers to monitor physiological changes before and after treatment. We still do not know which treatments or combinations of types of treatments will
Future directions
In the past 10 years,119 much progress has been made with diagnosis and management of autism spectrum disorder. Hopefully, early detection and diagnosis of infants and children at risk will enable treatments to be designed and implemented to alter the course of early behaviour and brain development.85 Amaral and colleagues120 suggested that the heterogeneity of factors affecting brain development predicts a heterogeneous pattern of neuropathology. Through neuroimaging approaches such as
Search strategy and selection criteria
References (120)
- et al.
Prevalence of disorders of the autism spectrum in a population cohort of children in South Thames: the Special Needs and Autism Project (SNAP)
Lancet
(2006) - et al.
Autism
Lancet
(2003) - et al.
Psychiatric disorders in children with autism spectrum disorders: prevalence, comorbidity, and associated factors in a population-derived sample
J Am Acad Child Adolesc Psychiatry
(2008) - et al.
Validation of the social communication questionnaire in a population cohort of children with autism spectrum disorders
J Am Acad Child Adolesc Psychiatry
(2007) - et al.
The developmental, dimensional and diagnostic interview (3di): a novel computerized assessment for autism spectrum disorders
J Am Acad Child Adolesc Psychiatry
(2004) - et al.
Genetics evaluation for the etiologic diagnosis of autism spectrum disorders
Genet Med
(2008) Developmental deficits in social perception in autism: the role of the amygdala and fusiform face area
Int J Dev Neurosci
(2005)- et al.
Electrophysiological signatures: magnetoencephalographic studies of the neural correlates of language impairment in autism spectrum disorders
Int J Psychophysiol
(2008) - et al.
Neurochemical correlates of autistic disorder: A review of the literature
Res Dev Disabi
(2006) - et al.
Structural variation of chromosomes in autism spectrum disorder
Am J Hum Genet
(2008)
Pharmacological rescue of synaptic plasticity, courtship behavior, and mushroom body defects in a Drosophila model of fragile X syndrome
Neuron
Interventions to improve communication in autism
Child Adolesc Psychiatr Clin N Am
An update on pharmacologic treatments for autism spectrum disorders
Child Adolesc Psychiatr Clin N Am
Diagnostic and statistical manual of mental disorders, 4th edn, text revision
The ICD-10 classification of mental and behavioral disorders: diagnostic criteria for research
Autism and related disorders: epidemiological findings in a Norwegian study using ICD-10 diagnostic criteria
J Autism Dev Disord
Brief report: autism and Asperger syndrome in seven-year-old children: a total population study
J Autism Dev Disord
The epidemiology of autism spectrum disorders
Annu Rev Public Health
Surveillance Summaries
MMWR Morbid Mortal Wkly Rep
The contribution of diagnostic substitution to the growing administrative prevalence of autism in US special education
Pediatrics
Autism and asperger syndrome: coexistence with other clinical disorders
Acta Psychiatr Scand
Psychotropic medication use among children with autism spectrum disorders
Pediatrics
Autism in infants: an update
World Psychiatry
Systematic review of early intensive behavioral interventions for children with autism
Am J Intellect Dev Disabil
Does routine child health surveillance contribute to the early detection of children with pervasive developmental disorders? An epidemiological study in Kent, UK
BMC Pediatr
Identification and evaluation of children with autism spectrum disorders
Pediatrics
The National Autism Plan for Children. Screening and assessment
Extraction and refinement strategy for detection of autism in 18-month-olds: a guarantee of higher sensitivity and specificity in the process of mass screening
J Child Psychol Psychiatry
A modified screening tool for autism (checklist for autism in toddlers [CHAT-23]) for Chinese children
Pediatrics
Evidence-based assessment of autism spectrum disorders in children and adolescents
J Clin Child Adolesc Psychol
Pennsylvania autism assessment and diagnosis expert work group: supporting quality diagnostic practices for persons with suspected autism spectrum disorder, 2007. Philadelphia, PA
Practitioner review: diagnosis of autism spectrum disorder in 2- and 3-year-old children
J Child Psychol Psychiatry
Prevalence and risk factors of maladaptive behaviour in young children with autistic disorder
J Intellect Disabil Res.
Parent reports of sensory symptoms in toddlers with autism and those with other developmental disorders
J Autism Dev Disord
Autism: definition, neurobiology, screening, diagnosis
Pediatr Clin North Am
Gastrointestinal symptoms in a sample of children with pervasive developmental disorders
J Autism Dev Disord
Atypical sleep architecture and the autism phenotype
Brain
The diagnosis of autism and Asperger syndrome: findings from a survey of 770 families
Dev Med Child Neurol
The Q-CHAT (Quantitative CHecklist for Autism in Toddlers): a normally distributed quantitative measure of autistic traits at 18–24 months of age: preliminary report
J Autism Dev Disord
The Modified Checklist for Autism in Toddlers: an initial study investigating the early detection of autism and pervasive developmental disorders.”
J Autism Dev Disord
A parent-report instrument for identifying one-year-olds at risk for an eventual diagnosis of autism: the first year inventory
J Autism Dev Disord
Screening for autism spectrum disorder with the Early Childhood Inventory-4
J Dev Behav Pediatr
Clinical utility of autism spectrum disorder scoring algorithms for the child symptom inventory-4
J Autism Dev Disord
ASDS Asperger syndrome diagnostic scale
Krug Asperger's Disorder Index
The autism spectrum quotient: children's version (AQ-Child)
J Autism Dev Disord
Childhood autism rating scale (CARS) and autism behavior checklist (ABC) correspondence and conflicts with DSM-IV criteria in diagnosis of autism.”
J Autism Dev Disord
Criterion-related and construct validity of the pervasive developmental disorders rating scale and the autism behavior checklist
Psychol Sch
The PDD-MRS: an instrument for identification of autism spectrum disorders in persons with mental retardation
J Autism Dev Disord
Short form of the developmental behaviour checklist
Am J Ment Retard
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