Diseases & Conditions


Autism Spectrum Disorder

Diseases & Conditions


What is autism spectrum disorder?

Autism spectrum disorder is an umbrella term for a group of complex disorders of brain development that can cause significant social, communication and behavioral challenges. It also includes restricted repetitive behaviors, interests and activities.

Autism spectrum disorder covers different brain disorders, such as:1

  • Autism
  • Asperger's syndrome
  • Childhood disintegrative disorder
  • Pervasive developmental disorder

Recent reviews estimate a global median prevalence of 62/10 000, that is one child in 160 has an autism spectrum disorder.1  


What causes autism spectrum disorder?

The exact cause of autism spectrum disorder is currently unknown. It is thought that both genetics factors and environmental factors could play a role in causing this disorder.2

  • Genetic factors: Genes are known to play a role in autism spectrum disorder. Children inherit some genes from their parents that could make them more prone to develop autism spectrum disorder.
  • Environmental factors: If a person has the genetic susceptibility to autism, some environmental factors could play a major role in developing the condition. These environmental factors include being born prematurely (before 35 weeks of pregnancy), or being exposed in the womb to alcohol or to certain medication.


What are the risk factors for autism spectrum disorder?

Factors that increase the risk of autism spectrum disorder:3

  • Gender: Boys face about four to five times higher risk than girls.
  • Family history: If one child in a family has autism spectrum disorder, this will increase the risk of having another child with the disorder.
  • Other disorders: Children with other syndromes have higher risks of developing autism spectrum disorder, such as
    • Fragile X syndrome: This is an inherited condition characterized by an X chromosome that is abnormally susceptible to damage. Affected individuals tend to have limited intellectual functions.
    • Tuberous sclerosis: This is a rare genetic disease that causes benign tumors to grow in the brain and on other vital organs such as the kidneys, heart, eyes, lungs, and skin.
    • Tourette syndrome: This is a neurological disorder characterized by repetitive, stereotyped, involuntary movements and vocalizations called tics.
    • Rett syndrome: This is a genetic condition occurring almost exclusively in girls, which causes slowing of head growth, intellectual disability and loss of purposeful hand use.
  • Premature babies: Babies born before 35 weeks of pregnancy may have a greater risk of autism spectrum disorder.


What are the symptoms of autism spectrum disorder?

Patients with autism spectrum disorder often have problems with social, emotional, and communication skills. Signs of autistic syndrome disorder begin in early childhood and include:4

Social impairment and communication difficulties:

  • Children fail to respond to their names
  • Avoid eye contact with other people
  • Interact only with others to achieve specific goals
  • Do not understand how to play or engage with other children
  • Prefer to be alone
  • Difficulty in understand other people’s feelings
  • Difficulties in talking about their own feelings
  • Different verbal abilities ranging from no speech to fluent speech but inappropriate
  • Delayed speech and language skills
  • Difficulties in using and understanding non-verbal cues such as gestures, body language, or tone of voice
  • Speaking in flat, robot-like or sing-song voice about a small range of subjects without taking into consideration the interests of the person with whom they are speaking

Repetitive and characteristic behaviors:

  • Repetitive movements
  • Unusual behavior such as flapping arms and rocking from side to side
  • Obsessive interest in a particular subject
  • Getting angry if placed in a new environment


How is autism spectrum disorder diagnosed?

Tests to diagnose spectrum disorder include:5

  • Observation of the child’s social interactions, communication skills and behavior
  • Tests covering speech, language, developmental level, and social issues
  • Tests to score the performance of communications interactions of the child
  • Genetic testing to identify whether the child has a genetic disorder such as fragile X syndrome.


How is autism spectrum disorder treated?

There are no medications that can cure autism spectrum disorder or treat the core symptoms. However, there are medications that can help some people with autism spectrum disorder function better. For example, medications might help manage high energy levels, inability to focus, depression, or seizures.6

Treatment includes behavior and communication therapies to address the social and language difficulties, educational therapies to improve social skills, family therapy to teach the parent how to interact with their children and medications to help control the symptoms of anxiety, hyperactivity and other behavioral problems.7



  1. WHO http://www.who.int/features/qa/85/en/ (Accessed February 23, 2016)
  2. Autism spectrum disorder http://www.nhs.uk/Conditions/Autistic-spectrum-disorder/Pages/Causes.aspx (Accessed February 23, 2016)
  3. Risk factors http://www.mayoclinic.org/diseases-conditions/autism-spectrum-disorder/basics/risk-factors/con-20021148 (Accessed February 23, 2016)
  4. Autism Spectrum Disorder Fact Sheet http://www.ninds.nih.gov/disorders/autism/detail_autism.htm#3082_2 (Accessed February 23, 2016)
  5. Tests and diagnosis http://www.mayoclinic.org/diseases-conditions/autism-spectrum-disorder/basics/tests-diagnosis/con-20021148 (Accessed February 23, 2016)
  6. Centers for Disease Control and Prevention http://www.cdc.gov/ncbddd/autism/treatment.html (Accessed February 23, 2016)
  7. Treatments and drugs http://www.mayoclinic.org/diseases-conditions/autism-spectrum-disorder/basics/treatment/con-20021148 (Accessed February 23, 2016)