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HannaRaaska
AnneSarajuuri

Autism Spectrum Disorder

Essentials

  • Autism spectrum disorder (ASD) is characterized by pervasive and persistent special features in social interaction and social communication as well as restricted, repetitive and inflexible patterns of behaviour, interests or activities.
  • The clinical picture, severity and effect on functional capacity vary greatly. About one in three patients show intellectual disability. Diagnosis and rehabilitation are required if the symptoms are severe enough to significantly affect functional capacity.
  • First symptoms of the disorder generally appear in childhood, but the symptoms may not become more clearly manifest until later, when social demands exceed the person's limited capacity, or support obtained for everyday life changes or because the person may have learned how to mask their autistic features.
  • A person should be referred for support and examinations as soon as suspicion arises. An autistic child, in particular, should be referred for any rehabilitation required as early as possible.

Autism spectrum in diagnostic classifications

  • In the ICD-10 disease classification, autism spectrum diagnoses are classified as pervasive developmental disorders (F84). The following ICD-10 diagnoses are currently considered as belonging to autism spectrum disorders:
    • childhood autism
    • atypical autism
    • Asperger's syndrome
    • other and unspecified pervasive developmental disorder.
  • Before the ICD-11 classification is taken into use, we recommend using the following diagnostic codes.
    • F84.0 Childhood autism, if core symptoms of an autism spectrum disorder are clearly manifest before the age of three years (understanding or producing speech for social communication, reciprocal social interaction, pretence)
    • F84.8 Other pervasive developmental disorder (autism spectrum disorder) in childhood, if there are pervasive and permanent special features in social interaction and communication, as well as restricted, repetitive and inflexible behavioural models, interests or activities but the diagnostic criteria for F84.0 are not completely fulfilled.
    • F84.9 Pervasive developmental disorder, unspecified (unspecified autism spectrum disorder) in childhood, if there are symptoms clearly suggesting an autism spectrum disorder but some investigations need to be completed or the direction of development followed
  • In the ICD-10 classification, Rett syndrome, other childhood disintegrative disorder and overactive disorder associated with mental retardation and stereotyped movements are also classified as pervasive developmental disorders.
  • The DSM-5 classification (published in 2013) contains autism spectrum disorder as an umbrella diagnosis, which is coded in more detail using information on developmental disability and language difficulties.
  • The ICD-11 classification, again, uses autism spectrum disorder as the name for the diagnosis. The diagnostic code is chosen depending on any intellectual disability and level of language use.
  • The diagnosis usually only becomes more specific during follow-up, particularly in the youngest children.

Epidemiology

  • According to a review article 4, the prevalence of ASD is 0.01-4.36% (median 1%). Most of the studies included were done on children and adolescents. ASD is more common in boys than in girls (with an estimated ratio of 4.2 : 1).
  • The numbers of ASD diagnoses and of children and adolescents being treated for ASD have been increasing gradually. This is believed to be largely due to external factors, such as increased availability of information, improved detection, increased availability of services, differences in entries in documents and changed diagnostic criteria, due to which the prevalence figures also include people with milder ASD with no intellectual disability.

Background

  • ASD is believed to be of multifactorial origin, caused jointly by genetic and external factors through epigenetic mechanisms, for instance.
  • Complications during pregnancy or delivery, exposure to valproate during pregnancy, and folic acid and vitamin D deficiency during pregnancy, as well as the parents' higher age are known to increase the risk of ASD.
  • In a family with one child with ASD, if no reason explaining it is found, the risk of ASD in any following siblings is about 10%. In addition, the risk of other developmental or psychiatric disorders is about 20-25%.
  • Several gene mutations that may be common or rare on population level have been described as underlying ASD but it is rarely due to any single gene defect or chromosomal abnormality.
  • In a small proportion of patients, the cause of the brain dysfunction is known (e.g. known chromosomal abnormality, fragile-X syndrome or some other known syndrome, metabolic disease, prematurity and related problems).

Symptoms

  • Autism spectrum disorder is a lifelong condition but presents individually, and its forms and effects on functional ability may change with age. Its severity varies greatly.
  • There are special features affecting functional capacity in social interaction and communication, as well as restricted, repetitive and inflexible patterns of behaviour, interests or activities.
  • In girls and women, symptoms may be atypical and more difficult to recognize and to diagnose.
  • Early childhood
    • If autism spectrum symptoms are seen in early childhood, already, functional capacity is often significantly affected.
    • In early childhood, abnormal reciprocal social interaction may present in the following ways, for example:
      • The use of eye contact, facial expressions and gestures is limited.
      • The child keeps to him- or herself in the company of others.
      • Shared attention is minimal or lacking (the child does not adjust his/her gaze to follow pointing, e.g. to an object or person).
      • The child has difficulty putting him-/herself into another person's position.
      • The child lacks the skill to imitate.
    • Underdevelopment in communication and speech may present as follows, for example:
      • There is no babbling, gesticulation or spoken language, or the spoken language is deviant (e.g. consisting of mechanically repeated stock phrases).
      • The child does not compensate for lacking or scanty speech by other forms of expression, such as gestures or facial expressions.
      • Interactive dialogue skills are deficient.
    • Activity is typically stereotypic and repetitive, and objects of interest may be narrow.
      • Stereotypic movements of the body or hands
      • Persistent interest in parts of objects
      • Play based on imagination and roles deficient; play consists rather of arranging and examining
      • Significant anxiety triggered by small changes in the environment
    • Other common symptoms
      • Fears, sleeping and eating disorders
      • Fits of rage, aggression or self-destructiveness
    • The level of intellectual ability varies. Approximately one in three children with ASD have intellectual disability. The level of linguistic ability is usually clearly lower than that of non-linguistic abilities.
    • The growth rate of the head circumference is accelerated in about 30% of patients in early preschool age but levels down later.
    • In about one third of autistic children there is retardation in the development of speech and language around the age of 1.5-2 years (reduced eye contact and interaction, words that the child had already learned may be left out of use).
  • Early preschool and school-age children
    • In addition to what was mentioned above, in early preschool and school-age children, the lack of reciprocal social interaction may appear as, for example:
      • less interest in social interaction
      • difficulty adjusting their behaviour to the situation, and approaching other children inappropriately even if interested in interaction
      • difficulty understanding other people's intentions, social modes of behaviour and rules and an appropriate distance to other people, and
      • lesser and abnormal reactions to requests presented by other people, their facial expressions or emotions.
    • The special features of the child's social communication may additionally appear in subtle specific difficulties.
      • The use of language for communication may be scanty, speech may be monotonous or repetitive. The child may use stock phrases, and the content of speech may focus on their own focuses of interest.
      • Difficulty in social communication may also appear as difficulty in reciprocal discussion.
      • The child will typically understand things literally, and sarcasm, humour or metaphors will be difficult to understand.
      • The child's ability to use gestures, expressions, body positions and eye contact may be restricted or weak.
    • Peculiar or restricted interests and inflexible and repetitive behaviour may appear in various ways.
      • Repetitive or stereotypic movements, such as flapping their arms, rocking their body, whirling, or snapping their fingers
      • Unusually intensive or restricted interests without a need to share them
      • A strong need to do things in their own way
      • Inappropriately strong emotional reactions
      • A strong need to hold on to familiar routines and to do things ‘just right'
      • Strong reaction to changes by anxiety or aggression
      • Excessive or insufficient reaction to sensations (such as noise, materials, tastes or smells); may appear as strong reactions to such sensations or to things such as materials or to how food looks.
    • The ability to use their imagination and to play may be restricted or scanty.
      • The child may pick content for play from TV programmes or from games, for example.
      • Play may be repetitive or stereotypical, focusing more on objects than on people.
      • It may be difficult for them to be flexible with play or play rules.
  • In adolescents, in addition to the above, the following features may suggest an autism spectrum disorder:
    • Difficulty with social interaction
      • The adolescent will speak to other people regardless of whether other people listen, and the adolescent's replies may appear rude or inappropriate.
      • It may be difficult for the adolescent to understand other people's intentions or purposes, and they may understand things literally.
      • Making friends or understanding friendship and social behaviour patterns may be difficult.
    • Exceptionally strong interest in certain things
    • Difficulty adjusting to changes, and stress caused by such changes
  • Adulthood
    • Diagnosis may be delayed until adulthood if the features are not clearly detectable during earlier development.
    • In adults, an autism spectrum disorder may be suggested by recurrent problems with social interaction and communication, inflexible and repetitive behaviour and difficulty tolerating changes, getting or keeping jobs or places of study or of creating or maintaining social relationships.

Diagnosis

  • Diagnosis is based on typical abnormalities in behaviour. If suspicion arises, investigations should be initiated and the person should be referred to the centre responsible for further investigations and diagnosis according to the regional guidelines and care pathway.
  • Diagnosis is based on careful multiprofessional assessment covering the following areas.
    • Collection of information about earlier developmental phases and the current situation (interviewing parents, teachers or other close people, using semistructured methods [such as ADI-R], other assessment forms, documents, as necessary)
    • Interviewing the person (considering the person's age and level of development and communication) about their symptoms and their own experiences, wishes and needs
    • Observing the core symptoms (also by the ADOS-2 method, for example)
    • Medical examination (somatic, neurological and psychiatric status), assessment of differential diagnosis, required aetiological examinations and any comorbidity
    • Other individual examinations, as necessary (for children, examination by a psychologist or neuropsychologist usually at least once, examination by speech, occupational and physiotherapists)
  • Associated/parallel diagnoses are common. These include, for example, attention deficit/hyperactivity disorder (ADHD) ADHD, various degrees of learning difficulties Learning Disorders, epilepsy Epilepsy in Children Diagnosis of Epilepsy: Definitions and Workup and psychiatric disorders. These should be considered when planning rehabilitation or medication.
  • The risk of many somatic diseases, such as cardiovascular diseases, endocrine disorders and allergies, as well as intestinal symptoms, is increased. Symptoms may be hard to identify, and the person's pain threshold may be high. In association with behavioural problems, the person's somatic health and the need for examinations should also be assessed.

Treatment and rehabilitation

  • Rehabilitation should be planned individually, considering functional problems, associated/parallel disorders, strengths and objects of interest, as well as the person's own motivation. The need for rehabilitation varies at different ages and stages of development.
  • Planning rehabilitation and the treatment of associated/parallel diseases is usually the responsibility of an expert team led by a specialist, according to the regional division of tasks.
  • Rehabilitation should focus on the symptoms and daily challenges most affecting the person's functional ability. Sufficient support should be offered for different daily environments (home, school, studies, work, leisure time). Modifying the environment so as to support the person's functional ability is an important part of support.
  • Support and modification of the environment as necessary should be started immediately when suspicion or worry of autism spectrum features arises.
    • It is essential for many children on the autism spectrum that using means of communication supporting or replacing speech (AAC or Augmentative and Alternative Communication methods) is begun as early as possible to support their linguistic and communication skills. Speech therapy in primary health care is often necessary already when waiting for diagnostic investigations.
    • Anticipation and a structured everyday life support executive skills and make the environment easier to understand.
    • Support for adults in their daily life includes, for example, professional support people, rehabilitation guidance, support for training and work, housing services, as well as supported or sheltered employment and day centres.
  • The aim of medical rehabilitation is to support skills that ensure the most independent life possible, achieving the person's own goals, and the development of a healthy self-esteem.
    • The type, methods and contents of rehabilitation should be chosen based on multiprofessional assessment and on targets set together with the person being rehabilitated and their close environment.
    • Common forms of rehabilitation include speech therapy and AAC guidance, occupational therapy, neuropsychological rehabilitation, cognitive behavioural therapy and interventions based on such therapy. Check also locally available rehabilitation services for different age groups and families.
    • Rehabilitation can be provided either individually or in a group.
    • Guidance of the parents and close environment, and providing rehabilitation in the children's or adolescents' natural environment are essential for as many people as possible in the close environment to enable them to implement rehabilitative methods and to facilitate more frequent application of skills in the daily environment through plenty of repetition.
  • Medication is not primarily recommended for core symptoms of autism spectrum disorders at any age. Pharmacotherapy may be necessary in the treatment of associated disorders, such as attention deficit/hyperactivity disorder ADHD, sleeping problems Insomnia or severe behavioural symptoms. The risk of adverse effects may be increased, and an adequate response may be achieved at lower doses than recommended.
  • The unit responsible for following up on rehabilitation should be agreed on even for steady stages so that specialized care can be consulted as necessary according to the regionally agreed division of tasks.

Other pervasive developmental disorders

  • As the official disease classification changes, these diagnoses will fall outside the diagnostic class of autism spectrum disorder.
  • Disintegrative disorder (Heller syndrome) http://www.orpha.net/en/disease/detail/168782
    • Rare
    • An extensive developmental disorder, in which a child whose development up to about the age of 3-5 years has been normal or almost normal rapidly becomes retarded, loses nearly all communication skills and shows symptoms that resemble autism, often also restlessness.
    • Progressive brain diseases and epileptic syndromes must be excluded.
  • Rett syndrome http://www.orpha.net/en/disease/detail/778
    • A developmental disability syndrome with severe symptoms occurring in girls. On symptom onset at the age of about 12 to 18 months autistic features and behavioural symptoms may be central. Other typical symptoms appear later.

    References

    • [Autism spectrum disorder]. A Current Care Guideline. Working group appointed by the Finnish Medical Society Duodecim, the Finnish Society for Child Psychiatry, the Finnish Society for Adolescent Psychiatry, the Finnish Society of Intellectual Disability Medicine, the Finnish Pediatric Neurology Association, and the Finnish Psychiatric Association. Helsinki: Finnish Medical Society Duodecim, 2023 (accessed 2.10.2023). Available in Finnish at http://www.kaypahoito.fi/hoi50131/.
    • Zeidan J, Fombonne E, Scorah J. Global prevalence of autism: A systematic review update. Autism Res 2022;15(5):778-790.
    • Fuentes J, Hervás A, Howlin P, et al. ESCAP practice guidance for autism: a summary of evidence-based recommendations for diagnosis and treatment. Eur Child Adolesc Psychiatry 2021;30(6):961-984 [PubMed]
    • Hyman SL, Levy SE, Myers SM, et al. Identification, Evaluation, and Management of Children With Autism Spectrum Disorder. Pediatrics 2020;145(1): [PubMed]
    • Lord C, Elsabbagh M, Baird G, et al. Autism spectrum disorder. Lancet 2018;392(10146):508-520 [PubMed]
    • de la Torre-Ubieta L, Won H, Stein JL et al. Advancing the understanding of autism disease mechanisms through genetics. Nat Med 2016;22(4):345-61. [PubMed]
    • Autism and Developmental Disabilities Monitoring Network Surveillance Year 2008 Principal Investigators, Centers for Disease Control and Prevention. Prevalence of autism spectrum disorders--Autism and Developmental Disabilities Monitoring Network, 14 sites, United States, 2008. MMWR Surveill Summ 2012;61(3):1-19 [PubMed]