Autism spectrum disorder: all you need to know

Autism spectrum disorders (ASD) is a development disorder characterized by a range of conditions and challenges with social skills, repetitive behaviors, speech and overall communication.

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Jan 31, 2019

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January 31, 2019
Charlotte Egeskov
Content Manager

Top things to know

  • Autism often occurs during the developmental period of childhood.
  • Individuals along the spectrum exhibit a full range of intellectual functioning and language abilities.
  • The identification of an autism spectrum disorder before 12 months of age is difficult. A diagnosis can be made around the age of 2 years.
  • Autism may be improved or individuals may better cope with their surroundings through different types of therapies and ABA (Applied Behavioral Analysis).
  • It is estimated that 1 out of 160 children has an autistic spectrum disorder, though recent studies report a significantly higher number.

What is autism?

Autism spectrum disorder (ASD) is a neurodevelopmental condition that “is characterized by persistent deficits in the ability to initiate and to sustain reciprocal social interaction and social communication” (1). The disorder is characterised by a range of restricted, repetitive and inflexible patterns of behaviour and interests. The degrees of ASD are extremely diverse and individuals along the spectrum exhibit a full range of intellectual functioning and language abilities.

The degrees of ASD are extremely diverse and individuals along the spectrum exhibit a full range of intellectual functioning and language abilities. ASD affects brain anatomy, functioning, and connectivity that all affects the behaviour across the individual’s lifespan. ASD can cause severe impairment in personal, family, social, educational, occupational or other important areas of functioning. Additionally, the capacities are usually “a pervasive feature of the individual’s functioning observable in all settings, although they may vary according to social, educational, or other context” (1).

Individuals with autism often have a co-morbid diagnosis such as atypical language development, sensory hypo or hypersensitivity and difficulties in motor coordination, including dyspraxia. Additionally, there is high comorbidity with ADHD, depression and suicidal ideation (2). However, on average, individuals with autism “tend to perform better on measures of ‘systemising’ drive that is, the drive to analyse and build systems, based on identifying the laws that govern the particular system, in order to predict how that system will work” (2). Individuals with autism also perform better on tests of attention to detail. Often individuals who are in the science-technology-engineering-maths fields are more likely to be diagnosed with autism or have autistic traits.

The causes of ASD are complex and include genetic and environmental risk factors (3). Often, autism occurs during the developmental period, typically in early childhood but may not manifest fully until later in life, when social demands exceed the capacities of the individual (1). While parents typically report concerns in the first year of life, many children do not receive diagnoses until much later. It is estimated that 1 out of 160 children has an autistic spectrum disorder, though recent studies report a significantly higher number (4). Moreover, boys are four times more likely to be diagnosed with ASD than girls (2).

Until recently, experts talked about different types of autism, such as Aspergers, Pervasive developmental disorder (PDD-NOS) and autistic disorder. But now, with the new ICD-11, the different types have been gathered under the term “autism spectrum disorders”. Within this category there are six distinctive expressions:

  1. Autism spectrum disorder without a disorder of the intellectual functioning or adaptive behaviour and with a mild impairment or no impairment in the individual's capacity to use functional language.

  2. Autism spectrum disorder with a mild or no impairment in the individual's capacity to use functional language.

  3. Autism spectrum disorder without a disorder of the intellectual functioning or adaptive behaviour and with a marked impairment in functional language.

  4. Autism spectrum disorder with a disorder of the intellectual functioning or adaptive behaviour and with a marked impairment in functional language.

  5. Autism spectrum disorder without a disorder of the intellectual functioning or adaptive behaviour and with acomplete, or almost complete, absence of ability relative to the individual’s age to use functional language.

  6. Autism spectrum disorder with a disorder of the intellectual functioning or adaptive behaviour and with a complete, or almost complete, absence of ability relative to the individual’s age to use functional language.

Autism symptoms: what you might notice

As mentioned ASD has a wide range of symptoms. Here the symptoms and signs of ASD (5):

  • Delayed speech development or doesn't speak at all
  • Repeats a set words and phrases
  • Talks "at" people, rather than having a two-way conversation
  • Not responding to their name
  • Rejecting cuddles initiated by a parent or carer (although they may initiate cuddles themselves)
  • Disliking people entering their personal space
  • Little to no interest interacting with others
  • Prefers to play alone
  • Rarely using gestures or facial expressions when communicating
  • Avoiding eye contact
  • Displaying repetitive movements, such as rocking back and forth
  • Playing with objects in a repetitive way, such as organizing or lining objects up
  • Prefers to have a familiar routine for each day
  • Unable to understand sarcasm, metaphors or figures of speech
  • Not understanding normal socially interactions like greetings and politeness
  • Develops a highly specific interest in a particular subject or activity

Causes of autism

The exact cause of ASD hasn’t been scientifically proven. Although, the cause is thought to be complex and includes genetic and environmental risk factors. “For instance, on the genetic level alone, more than 100 genetic and genomic loci* have been implicated in autism. However, the ways in which these risk factors lead to the biological differences underpinning ASD or whether they could provide crucial clues to help in the development of new treatments is unknown” (3). ASD is though a heritable condition where genes inherited from one or both parents can impact the development of an autistic brain. Regardless, there is some environmental - yet unknown - component interacting with the risk genes for Autism as the heritability isn’t 100 percent (6).

ASD is though a heritable condition where genes inherited from one or both parents can impact the development of an autistic brain. Regardless, there is some environmental - yet unknown - component interacting with the risk genes for Autism as the heritability isn’t 100 percent (6).

How is Autism diagnosed?

It isn’t easy to diagnose ASD as doctors or specialist have to observe a child’s behaviour and development over a period to make a diagnosis. The diagnosis process can vary depending on the age of the individual who is under observation. However, the diagnosis process is usually based on a combination of behavioural observations and clinical interviews that assess deficits in social communication, social reciprocity, and repetitive and stereotyped behaviours and interests.

Autism treatment: What can you do about the diagnosis?

There is no cure for Autism available. For most, the ASD diagnosis will stay with the individual throughout their life, though many will make progress with their condition as they grow (6). There has been no scientific proof that ASD can be cured completely, however, there are studies showing improvements of the condition through diet and therapies like
Early Intensive Behavioral Intervention (UCLA Model), Picture Exchange Communication System (PECS), Cognitive Behavioral Therapy, Pivotal Response Training, and Music therapy (6). In the ASD community there “there is growing consensus that the most effective interventions for children with ASD is to target core deficits (i.e., social communication); focus on individualized child goals; actively engage the child in multiple, planned learning opportunities throughout the day; incorporate the child’s interests; and involve multiple social-interaction partners, including parents“ (7). Moreover, early identification of ASD and treatment of Autism is important as specifically targeting early social communication behaviours, such as imitation in young children with ASD is beneficial.

In the ASD community there “there is growing consensus that the most effective interventions for children with ASD is to target core deficits (i.e., social communication); focus on individualized child goals; actively engage the child in multiple, planned learning opportunities throughout the day; incorporate the child’s interests; and involve multiple social-interaction partners, including parents“ (7)

*) A loci is plural for locus. Locus is a specific physical location of a gene or DNA sequence on a chromosome - like a genetic street address.

Until recently, experts talked about different types of autism, such as Aspergers, Pervasive developmental disorder (PDD-NOS) and autistic disorder. But now, with the new ICD-11, the different types have been gathered under the term “Autism spectrum disorders”. Diagnoses such as Aspergers, Atypical autism etc. from the ICD-10 are hereby old definitions of the autism spectrum and will cease the 1. January 2022 when ICD-11 takes effect.


  1. ICD-11 for Mortality and Morbidity Statistics, World Health Organization. Retrieved from https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/437815624.

  2. Baron-Cohen, S. (2017). The Genetics of Autism, Autism Research Centre. Retrieved from http://docs.autismresearchcentre.com/papers/2017WarrierThe-Genetics-of-Autism.pdf.

  3. Ecker, C., Bookheimer, S.Y. and Murphy, D.G.M., (2015). Neuroimaging in autism spectrum disorder: brain structure and function across the lifespan. The Lancet Neurology, 14(11), 1121-1134. https://doi.org/10.1016/s1474-4422(15)00050-2.

  4. Questions and answers about autism spectrum disorders (ASD), World Health Organization. Retrieved from https://www.who.int/features/qa/85/en/.

  5. Symptoms Autism, nhs.uk, https://www.nhs.uk/conditions/autism/symptoms/.

  6. Jaarsma, P. (2014). Reflections on Autism: Ethical Perspectives on Autism Spectrum Disorder in Health Care and Education. Linköping Studies in Arts and Science no. 606. Retrieved from https://www.diva-portal.org/smash/get/diva2:696956/FULLTEXT01.pdf.

  7. Ingersoll, B. (2011). Recent Advances in Early Identification and Treatment of Autism. Current Directions in Psychological Science, 20, 335. https://doi.org/10.1177/0963721411418470

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