Elsevier

The Lancet

Volume 383, Issue 9920, 8ā€“14 March 2014, Pages 896-910
The Lancet

Seminar
Autism

https://doi.org/10.1016/S0140-6736(13)61539-1Get rights and content

Summary

Autism is a set of heterogeneous neurodevelopmental conditions, characterised by early-onset difficulties in social communication and unusually restricted, repetitive behaviour and interests. The worldwide population prevalence is about 1%. Autism affects more male than female individuals, and comorbidity is common (>70% have concurrent conditions). Individuals with autism have atypical cognitive profiles, such as impaired social cognition and social perception, executive dysfunction, and atypical perceptual and information processing. These profiles are underpinned by atypical neural development at the systems level. Genetics has a key role in the aetiology of autism, in conjunction with developmentally early environmental factors. Large-effect rare mutations and small-effect common variants contribute to risk. Assessment needs to be multidisciplinary and developmental, and early detection is essential for early intervention. Early comprehensive and targeted behavioural interventions can improve social communication and reduce anxiety and aggression. Drugs can reduce comorbid symptoms, but do not directly improve social communication. Creation of a supportive environment that accepts and respects that the individual is different is crucial.

Section snippets

Definition

In 1943, child psychiatrist Leo Kanner described eight boys and three girls,1 including 5-year-old Donald who was ā€œhappiest when left alone, almost never cried to go with his mother, did not seem to notice his father's home-comings, and was indifferent to visiting relativesā€¦wandered about smiling, making stereotyped movements with his fingersā€¦spun with great pleasure anything he could seize upon to spinā€¦. Words to him had a specifically literal, inflexible meaningā€¦. When taken into a room, he

Prevalence

The prevalence of autism has been steadily increasing since the first epidemiological study,7 which showed that 4Ā·1 of every 10ā€ˆ000 individuals in the UK had autism. The increase is probably partly a result of changes in diagnostic concepts and criteria.8 However, the prevalence has continued to rise in the past two decades, particularly in individuals without intellectual disability, despite consistent use of DSM-IV criteria.9 An increase in risk factors cannot be ruled out. However, the rise

Prognosis and outcome

A meta-analysis63 showed that individuals with autism have a mortality risk that is 2Ā·8 times higher (95% CI 1Ā·8ā€“4Ā·2) than that of unaffected people of the same age and sex. This difference is mostly related to co-occurring medical conditions.64 Studies done before the widespread application of early intervention programmes65, 66, 67 showed that 58ā€“78% of adults with autism have poor or very poor outcomes in terms of independent living, educational attainment, employment, and peer

Early signs and screening

Early identification allows early intervention. Previously, children with autism were often identified when older than 3ā€“4 years, but toddlers are now frequently diagnosed because atypical development is recognised early. Early indicators are deficits or delays in the emergence of joint attention (ie, shared focus on an object) and pretend play, atypical implicit perspective taking, deficits in reciprocal affective behaviour, decreased response to own name, decreased imitation, delayed verbal

Clinical assessment

Diagnostic assessment should be multidisciplinary and use a developmental framework of an interview with the parent or caregiver, interaction with the individual, collection of information about behaviour in community settings (eg, school reports and job performance), cognitive assessments, and a medical examination.92 Co-occurring conditions should be carefully screened.

The interview of the parent or caregiver should cover the gestational, birth, developmental, and health history, and family

Cognition and neuroscience

In the mid-20th century, autism was thought to originate from the emotional coldness of the child's mother, even though this hypothesis had no empirical support. By contrast, concurrent neurobiological hypotheses96 and Kanner's proposal of an ā€œinnate inability to form the usual, biologically provided affective contact with peopleā€1 have received scientific support. Cognition and neurobiology are related, and their development is characterised by a complex interplay between innate and

Neurobiology

Neurobiological investigation has identified patterns of brain perfusion and neural biochemical characteristics, which are described elsewhere.118, 119 Additionally, systems-level connectivity features and plausible neuroanatomical, cellular, and molecular underpinnings of autism have been identified. Evidence from electrophysiology and functional neuroimaging (resting-state and task-based connectivity),120 structural neuroimaging (white-matter volume and microstructural properties),121, 122,

Genetics

Twin studies have suggested that autism has high heritability (more than 80%).148 This heritability occurs in the context of environmental risks and geneā€“environment interplay,33 because the monozygotic concordance rates are never 100%. Epigenetic mechanisms and specific geneā€“environment interplay are important but understudied. From an evolutionary viewpoint, autistic traits could have been subject to positive selection pressure,149 because of the potential benefits of a solitary single-minded

Overview

Intervention and support should be individualised and, if appropriate, multidimensional and multidisciplinary. The goals are to maximise an individual's functional independence and quality of life through development and learning, improvements in social skills and communication, reductions in disability and comorbidity, promotion of independence, and provision of support to families. Additionally, individuals should be helped to fulfil their potential in areas of strength. Although autism is

Conclusions

Understanding of autism has changed substantially in the 70 years since it was first described. With the recent exponential increase in research and the inclusion of scientists from a wide range of disciplines, understanding will continue to evolve at an accelerated rate. The specialty has achieved much: it has reached a consensus about behavioural definition; accepted the increased prevalence; improved understanding about early presentation; established systematic clinical assessments and

Search strategy and selection criteria

We searched PubMed, PsycINFO, the Cochrane Library, and Google Scholar for reports published between Jan 1, 2000, and June 20, 2013. We used the search terms ā€œautismā€, ā€œautism spectrum disorderā€, ā€œpervasive developmental disorderā€, and ā€œAsperger syndromeā€. We searched for other relevant earlier reports in the reference lists of reports identified through the database search. We mainly report summary findings from systematic reviews, meta-analyses, authoritative book chapters, and research

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