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What is autism?

Autism is a neurobiological disorder that affects the brain. Autism is characterized by social and language challenges and excessively repetitive routines and behaviors. For example, a person with autism may have an obsession with a certain topic, such as airplanes, and have high-energy temper tantrums. A person with autism may also have problems making eye contact, or may show you he or she is happy by spinning around instead of smiling.

Autism encompasses a group of disorders called autism spectrum disorders (ASDs), which includes these related disorders:

  • Autistic disorder is also referred to as classic autism and is the most debilitating form of autism.

  • Asperger syndrome, also known as Asperger’s, is sometimes called high-functioning autism. People with Asperger’s typically have social challenges and display repetitive behaviors, but they have fewer challenges with language and communication than people with classic autistic disorder.

  • Pervasive developmental disorder not otherwise specified is also referred to as PDD-NOS, or atypical autism. PDD-NOS is often thought of as a milder form of autism, where not all the autism criteria are met during diagnosis.

The symptoms and severity of autism vary greatly from child to child and among the different forms of ASD. Symptoms appear in early childhood and continue throughout one’s lifetime.

ASDs occur in both genders, but boys are more likely to have an ASD than girls. ASDs also appear in all ethnicities, socioeconomic levels, and geographic areas. The Centers for Disease Control and Prevention (CDC) estimates that one in 110 children in the United States has autism or ASD (about 730,000 people from birth to 21 years of age) (Source: CDC).

Autism and ASDs take a great toll on children and their families. Little is known about what causes autism and ASDs. While research continues on the myriad of possible causes, the scientific community recognizes that ASDs are not caused by bad parenting.

There is no cure for autism or ASDs at this time, although a variety of therapies and other treatments are available to help people with autism and their families live as full and normal lives as possible. Researchers around the world are studying autism to learn more about the causes and treatment of autism and ASDs.

Seek prompt medical careif your child has symptoms of autism, such as delays in normal development or lack of language or social skills. In certain situations, people with autism can exhibit aggressive tendencies. Seek immediate medical care (call 911) if someone you are with or know becomes violent, threatening, or dangerously aggressive, or is hurting himself or herself.


What are the symptoms of autism

Symptoms of autism begin early in life. Parents of children with autism generally notice symptoms of autism by their child’s first or second birthday.

Characteristic symptoms of the most severe type of autism, called autistic disorder, include social and language problems, abnormally repetitive routines and behaviors, and extreme sensory feelings. However, specific behaviors and characteristics vary greatly from person to person.

Symptoms of other types of autism spectrum disorders (ASDs) also vary in nature and severity. For example, people with Asperger syndrome typically have social challenges and display repetitive behaviors, but they have fewer challenges with language and communication than those with autistic disorder. People with pervasive developmental disorder not otherwise specified (PDD-NOS) do not have many of the symptoms of autistic disorder, and their symptoms tend to be milder as well.

Communication and language symptoms of autism

Many people with autism find it difficult to communicate. They might have problems understanding other people, or in using more subtle communication methods like facial expressions, movements, and gestures. The following are specific communication-related symptoms of autism:

  • Answers questions with unrelated answers

  • Communicates with gestures instead of words or vice versa

  • Does not develop language or develops it very slowly

  • Does not understand or use social cues including facial expressions and gestures

  • Interprets what other people say very literally, and does not easily understand jokes or irony

  • Repeats his or her own words or phrases over and over, or repeats what other people say

  • Uses pronouns incorrectly (such as “You would like some water” instead of “I would like some water”)

Social symptoms of autism

People with autism have social habits that are more debilitating than everyday idiosyncrasies. Autistic people often exhibit social tendencies that include:

  • Dislike of physical contact

  • Inability to maintain eye contact

  • Lack of empathy, which is the ability to understand other people’s feelings

  • Solitary play; autistic individuals do not make friends easily

Behavioral symptoms of autism

Behaviors that many people with autism exhibit include:

  • Abnormally sensitive or insensitive to the way things look, feel, sound, taste or smell

  • Aggressive and violent temper tantrums

  • Attachment to routines, and inability to cope if things happen outside the routine

  • Attachment to certain objects

  • Extreme impulsivity and hyperactivity

  • Obsessive interest in certain objects or topics (for example, insects)

  • Repetitive or inappropriate activities (for example, licking all the windows on toy cars)

  • Repetitive body movements, such as rocking, flapping arms, rubbing fingers together, and spinning in circles

  • Self-abusive behaviors, such as head banging and biting

Serious symptoms that might indicate a dangerous or life-threatening condition

In some cases, a child or adult with autism can become violent and a danger to himself or herself or others. Seek immediate medical care (call 911) if someone you are with or know has any of these symptoms:

  • Suicidal thoughts or a desire to hurt oneself or others

  • Violent or threatening behavior


What causes autism?

The medical community does not definitively know what causes autism and the range of autism spectrum disorders (ASDs). Autism and ASDs are known to be complex, so it is likely they have multiple interconnected causes. Scientists and researchers are exploring thousands of environmental and genetic influences on fetuses, infants and children that may make them more likely to develop an ASD. The specific influences under investigation include medications, other medical conditions, viruses, and chromosomal abnormalities. It is, however, generally accepted by medical providers that poor parenting practices do not cause autism.

There has also been a significant amount of discussion and research about whether childhood vaccines are linked to autism. The Centers for Disease Control and Prevention (CDC), The American Academy of Pediatrics, and The Institute of Medicine (IOM) all state that no research has shown an association between vaccines and the development of ASDs, and that the benefits of vaccines outweigh any risks from them (Source: CDC).

What are the risk factors for autism?

The cause of autism and autism spectrum disorders (ASDs) is not yet known. Research is active and wide-ranging to identify what makes a person more likely to develop an ASD. However, there are two known risk factors for developing an ASD:

  • Family history, such as a parent or sibling with an ASD

  • Male gender

  • There are also co-occurring diseases that develop in a small percentage of people with autism. They include:

  • Epilepsy (brain disorder characterized by strange sensations, behaviors and seizures)

  • Fragile X syndrome (inherited form of mental impairment)

  • Intellectual and developmental disabilities (IDDs) such as Down syndrome

  • Tuberous sclerosis (genetic disorder that leads to benign, noncancerous tumors in the central nervous system)


How is autism treated?

There is no cure for autism or autism spectrum disorders (ASDs), but there are several therapies available that can help an autistic child’s development and behavior. The goals of autism treatment may include managing tantrums, learning social skills, and helping improve focus and attention span. Each person with autism has unique behaviors and symptoms, and requires a personalized treatment plan developed with his or her family by a team of doctors, therapists and educators. In general, treatment is more successful the earlier it is begun after diagnosis.

Behavioral, educational and physical therapies

The following types of therapies can help people with ASDs refine their social skills, adapt to changes in their environment, learn everyday life skills, such as dressing and bathing, and improve communication. Therapies include:

  • Applied behavioral analysis

  • Occupational therapy

  • Physical therapy

  • Sensory integration therapy

  • Speech therapy


Medications cannot cure autism, but they are used to lessen the severity of certain symptoms associated with the disorder, such as anxiety, hyperactivity, aggression, and mood swings. Medications that might help mitigate these symptoms include:

  • Anti-anxiety medications

  • Antidepressants

  • Antipsychotic medications

  • Stimulants

Other therapies

Some families have found that certain therapies can help improve symptoms associated with autism and ASDs. Other therapies may include dietary changes, massage therapy, and alternative medicines. Many of these are unproven by scientific research; they may reduce symptoms in some people and worsen symptoms in others. You can minimize the risk of serious complications associated with any therapy or treatment by following the treatment plan you and your autism treatment team design specifically for your family.

What are the possible complications of autism?

With time, many symptoms of autism can improve. However, if a person does not receive adequate treatment or support for his or her autism, complications can include: 

  • Chronic stress

  • Depression

  • Disability

  • Increasingly disruptive behaviors and habits

  • Lasting effects of self-injury
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2018 Oct 31
  1. Autism. PubMed Health, a service of the NLM from the NIH.
  2. Autism Fact Sheet. National Institute of Neurological Disorders and Stroke.
  3. Autism Spectrum Disorder (ASD): Overview. Eunice Kennedy Shriver National Institute of Child Health & Human Development.  
  4. Autism Spectrum Disorder (ASD).The Centers for Disease Prevention and Control and Prevention.  
  5. NINDS Epilepsy Information Page. National Institute of Neurological Disorders and Stroke.
  6. NINDS Tuberous Sclerosis Information Page. National Institute of Neurological Disorders and Stroke.
  7. Landa RJ, Gross AL, Stuart EA, Faherty A. Developmental trajectories in children with and without autism spectrum disorders: the first 3 years. Child Dev 2013; 84:429.
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