ASD caused by problems with how the brain developed. Why this happens is not known. It may be caused by genetics or problems during pregnancy, such as infection.

Infant Brain—Period of Rapid Development
Infant Brain and skull
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Risk Factors

ASD is more common in boys. Other things that may raise the risk are:

  • Having a sibling who has ASD
  • Having a mother who is at least 40 years of age or a father who is at least 50 years of age
  • Problems during pregnancy or delivery
  • Genetic issues

Many people with ASD also have other developmental, medical, or mental health problems. The reason why is not known.



ASD often appears between 2 to 6 years old. Symptoms vary from person to person, but may include:

  • Communication and social interaction issues, such as:
    • Not making eye contact
    • Not listening to others
    • Not pointing or showing things to others
    • Not responding to others, such as when a person's name is called
    • Problems with back and forth communication
    • Talking about the same thing for a long time without noticing others are not interested
    • Having body language that does not match what is being said
    • Having a strange tone of voice, such as like a robot
    • Not understanding another person's feelings and needs
  • Narrow interests and behaviors, such as:
    • Repeating behaviors or having strange behaviors, such as repeating words or phrases
    • Having a strong interest in specific topics
    • Getting upset by small changes in routine
    • Being sensitive to sensory input, such as noise


The doctor will ask about symptoms and past health. There may also be questions about behavior, social skills, and communication abilities. Parents will be asked about their child's behavior. A physical will be done.

Tests will be done to learn more about how the person's brain works. This can be done with neuropsychological tests. The tests will be given by a care team that is experienced in diagnosing ASD.

These tests may be done to rule out health problems that have similar symptoms:

  • Blood tests
  • Hearing tests

An electroencephalogram (EEG) may also be done to record brain activity.



The goal of treatment is to help a person's quality of life. With treatment, many people can learn how to cope with ASD. They may be able to work and live on their own. Others may need support throughout their lives.

Symptoms may decrease over the years. Treatment should be started early. It may include:

  • Speech, physical, or occupational therapy to improve function
  • Social skills training to help how a person relates to others
  • Applied behavioral analysis to improve behaviors, such as communication and social skills
  • Services that provide support in school
  • Mental health counseling
  • Medicine to help manage symptoms, such as anxiety


There are no current guidelines to prevent ASD.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.