Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurological and developmental disorder that affects how people interact with others, communicate, learn, and behave. Although autism can be a lifelong disorder, treatments, services, and support can improve a person’s health, well-being, and daily functioning.

Overview

Autism spectrum disorder (ASD) is a neurological and developmental disorder that affects how people interact with others, communicate, learn, and behave. Although autism can be diagnosed at any age, it is described as a “developmental disorder” because symptoms generally appear in the first two years of life.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a guide created by the American Psychiatric Association that healthcare providers use to diagnose mental disorders and developmental disorders, people with autism spectrum disorder often have:

  • Difficulty with social communication and interaction with other people
  • Restricted interests and repetitive behaviors
  • Symptoms that affect their ability to function at school, work, and in other areas of life

Autism is known as a “spectrum” disorder because people with autism have a range of characteristics, needs, strengths, and challenges.

People of all ages, races, ethnicities, sexes, and economic backgrounds can be diagnosed with autism. Although autism can be a lifelong disorder, treatments, services, and support can improve a person’s health, well-being, and daily functioning. The American Academy of Pediatrics recommends that all children receive screening for autism. Caregivers should talk to their child’s healthcare provider about autism screening or evaluation.

Signs and Symptoms

The list below gives some examples of different types of behaviors that are common among people diagnosed with ASD. Not all people with ASD will have all behaviors, but most will have several of the behaviors listed below.

Social communication and social interaction behaviors may include:

  • Making little or inconsistent eye contact
  • Appearing not to look at or listen to people who are talking
  • Infrequently sharing interest, emotion, or enjoyment of objects or activities (including infrequently pointing at or showing things to others)
  • Not responding or being slow to respond to one’s name or other verbal bids for attention
  • Having difficulty with the back and forth of conversation
  • Often talking at length about a subject of interest without considering social cues or conversational give-and-take
  • Displaying facial expressions, movements, and gestures that do not match what is being said
  • Having an unusual tone of voice that may sound flat, lacking emotion, or tonal variation
  • Having trouble understanding another person’s point of view or being unable to predict or understand other people’s actions
  • Difficulty adjusting behavior to different social situations
  • Difficulty sharing in imaginative play or making friends

Restrictive/repetitive behaviors may include:

  • Repeating certain words or having unusual behaviors, such as repeating words or phrases (a behavior called echolalia)
  • Having a lasting, intense interest in specific topics, such as numbers, details, or facts
  • Showing overly focused interests, such as with moving objects or with parts of objects
  • Becoming upset by slight changes in a routine and having difficulty with transitions

People with autism often have sensory differences such as:

  • Being more sensitive or less sensitive than other people to sensory input, such as light, sound, clothing, or temperature

People with ASD also may experience sleep problems and irritability.

People with autism may also have many strengths, including:

  • Being able to learn things in detail and remember information for long periods of time
  • Being strong visual and auditory learners
  • Excelling in math, science, technology, music, or art

Related Health Effects

Some people with ASD also have co-occurring physical and mental health conditions that can impact daily life. These may include:

  • Epilepsy or seizure disorder: Some people with autism show signs of epilepsy by adulthood. In most cases, medicine can control and treat epilepsy effectively.
  • Tuberous sclerosis: A small percentage of people with ASD also have tuberous sclerosis. This is a disorder that causes non-cancerous tumors to grow in the brain, kidneys, liver, heart, lungs, and skin. People with tuberous sclerosis have some of the same symptoms as some people with ASD, including developmental delay, behavior problems, and seizures.
  • Fragile X syndrome: A small percentage of people with ASD also have Fragile X syndrome, the most common inherited form of intellectual disability.
  • Intellectual disability: Many people with ASD have an intellectual disability (problems with thinking, remembering, concentrating, or being creative).
  • Anxiety: Many children with autism have an anxiety disorder. Each anxiety disorder has different symptoms, but in general, anxiety disorders cause people to feel excessive and irrational fear and dread.
  • Attention-deficit/hyperactivity disorder (ADHD): Many children with autism also have ADHD. Symptoms include difficulty staying focused and paying attention, difficulty controlling behavior, and hyperactivity (overactivity).
  • Sleep disorders: Many people with ASD also may experience sleep problems.
  • Allergies, Immune, and Autoimmune conditions: Many people with ASD also may experience allergies, changes in their immune function, or auto-immune disorders.
  • Gastrointestinal issues: Some people with ASD have digestive problems, such as constipation, abdominal pain, or vomiting.

Although many of these problems are addressable, treatments for these conditions won't cure autism, but they can improve the quality. Learn about how to talk with a doctor or healthcare practitioner about mental health.

Causes

Because the disorder is so complex and no two people with autism are exactly alike, there are probably many causes for autism, rather than any one cause. For an individual, there is also likely no single cause for autism, but rather, it results from a combination of factors.

Genetic and Biological Factors

A great deal of evidence supports the idea that genes are one of the main contributors to autism. Having a sibling with ASD increases the likelihood for autism. More than 100 genes on different chromosomes may be involved in causing autism to different degrees.

Many people with autism have slight changes, called mutations, in many of these genes. However, the link between genetic mutations and autism is complex:

  • Most people with autism have different mutations and combinations of mutations. Not everyone with autism has changes in every gene that scientists have linked to ASD.
  • Many people without autism or autism symptoms also have some of these genetic mutations that scientists have linked to autism.

This evidence means that different genetic mutations probably play different roles in ASD. For example, certain mutations or combinations of mutations might:

  • Cause specific symptoms of ASD
  • Control how mild or severe those symptoms are
  • Increase susceptibility to autism: Someone with one of these gene mutations is at greater risk for autism than someone without the mutation.

Additionally, some chromosomal disorders, such as Down Syndrome and Fragile X, are also associated with autism.

If someone is susceptible to ASD because of genetic mutations, then certain situations might increase their likelihood of developing autism. For instance, an infection or contact with chemicals in the environment could increase the likelihood of autism in someone who is susceptible because of genetic mutations. However, someone who is genetically susceptible might not develop autism even if he or she has the same experiences.

The American Academy of Pediatrics and other professional organizations recommend genetic assessment for all children with an autism diagnosis, particularly if there is also developmental delay.

Researchers are also looking into biological factors other than genes that might be involved in ASD. Some of these include:

  • Problems with brain connections
  • Problems with growth or overgrowth in certain areas of the brain
  • Problems with metabolism (the body’s energy production system)
  • Problems in the body’s immune system, which protects against infections

Environmental Factors

Some environmental factors associated with increased likelihood of autism include:

  • Advanced parental age at time of conception
  • Prenatal exposure to air pollution or certain pesticides
  • Maternal obesity, diabetes, or immune system disorders
  • Extreme prematurity or very low birth weight
  • Any birth difficulty leading to periods of oxygen deprivation to the baby’s brain
  • Insufficient thyroid hormone or hypothyroidism in pregnancy, which is the most common preventable cause of cognitive and related disorders

These factors alone are unlikely to cause autism. Rather, they appear to increase a child’s likelihood of developing autism when combined with genetic factors. A growing area of research focuses on the interaction of genetic and environmental factors.

Other Factors

Some factors associated with an increased likelihood of developing autism include:

  • Having older parents
  • Having a very low birth weight

Currently, there is no scientific evidence that vaccines or any material used to make or preserve vaccines causes or contributes to autism. This includes vaccines containing thimerosal, a mercury-based compound. 

NIH-funded studies have found that taking prenatal vitamins may help lower the likelihood of autism diagnosis. Specifically:

  • Women were less likely to have a child with autism if they took a daily prenatal vitamin during the three months before and the first month of pregnancy.
  • Women who took the daily recommended dosage of folic acid during the first month of pregnancy were less likely to have a child with autism.

Diagnosis

Healthcare providers diagnose ASD by evaluating a person’s behavior and development. ASD can usually be reliably diagnosed by the age of 2. It is important to seek an evaluation as soon as possible. The earlier ASD is diagnosed, the sooner treatments and services can begin.

Diagnosis in Young Children

Diagnosis in young children is often a two-stage process.

Stage 1: General developmental screening during well-child checkups. Every child should receive well-child checkups with a pediatrician or an early childhood healthcare provider. The American Academy of Pediatrics recommends that all children receive screening for developmental delays at their 9-, 18-, and 24- or 30-month well-child visits, with specific autism screenings at the 18- and 24-month well-child visits. A child may receive additional screenings if they have an increased likelihood of developing ASD or developmental problems.

Considering caregiver experiences and concerns is an important part of the screening process for young children. The healthcare provider may ask questions about the child’s behaviors and evaluate those answers together with information from ASD screening tools and clinical observations of the child. Learn more about ASD screening on the Centers for Disease Control and Prevention (CDC) website.

The healthcare provider may refer the child for additional evaluation if they show developmental differences in behavior or functioning during this screening process.

Stage 2: Additional diagnostic evaluation. A team of healthcare providers who have experience diagnosing ASD will conduct this evaluation. This team may include child neurologists, developmental behavioral pediatricians, speech-language pathologists, child psychologists and psychiatrists, educational specialists, and occupational therapists.

The diagnostic evaluation is likely to include:

  • Medical and neurological examinations
  • Assessment of cognitive abilities
  • Assessment of speech and language abilities
  • Observation of behavior
  • An in-depth conversation with caregivers about the child’s behavior and development
  • Assessment of age-appropriate skills needed to complete daily activities independently, such as eating, dressing, and toileting
  • Questions about the child’s family history
  • Blood tests and a hearing test, if needed, as ASD is a complex disorder that sometimes occurs with other conditions or learning disorders

The outcome of this evaluation may result in a formal diagnosis and recommendations for treatment.

Diagnosis in Older Children and Adolescents

Caregivers and teachers are often the first to recognize ASD symptoms in older children and adolescents. The school’s special education team may perform an initial evaluation and then recommend that a child receives additional evaluation from their primary healthcare provider or a healthcare provider who specializes in ASD.

A child’s caregiver may talk with these healthcare providers about the child’s social difficulties, including problems with subtle communication. Older children and adolescents may display subtle communication differences that may include problems understanding tone of voice, facial expressions, body language, figures of speech, humor, or sarcasm. They also may have challenges forming friendships with peers.

It is also important for the healthcare provider to learn about the child’s strengths so they can tailor their recommendations for services and supports.

Diagnosis in Adults

Diagnosing ASD in adults is often more difficult than diagnosing ASD in children. In adults, some ASD symptoms can overlap with symptoms of mental disorders such as an anxiety disorder or attention-deficit/hyperactivity disorder (ADHD).

Adults who have questions about whether they may be on the autism spectrum should talk with a healthcare provider and ask for a referral for an ASD evaluation. Although evaluation for ASD in adults is still being refined, adults can be referred to a neuropsychologist, psychologist, or psychiatrist who has experience with ASD. The expert will ask about:

  • Social interaction and communication challenges
  • Sensory issues
  • Repetitive behaviors
  • Restricted interests

The evaluation may also include a conversation with caregivers and family members to learn about the person’s early developmental history, which can help ensure an accurate diagnosis.

Obtaining a correct diagnosis of ASD as an adult can help people understand past challenges, identify personal strengths, and find the right kind of help. Studies are underway to determine the types of services and supports that are most helpful for transition-age youth and adults with autism.

Treatment and Management

There is currently no standard treatment for ASD. But there are many ways to help minimize the symptoms and maximize abilities. Therapies, services, and supports can improve a person’s health, well-being, and daily functioning. Most people with autism respond best to highly structured and specialized programs. Interventions are most effective when they begin as soon as possible after diagnosis. People of all ages can benefit from treatment, no matter how old they are when they are diagnosed.

A variety of therapies can help people with autism improve their daily life skills:

  • Speech-language therapy helps improve verbal and nonverbal communication skills. Such skills include correctly naming people and things, better explaining feelings and emotions, using words and sentences better, and improving the rate and rhythm of speech. Some children with autism may need to use alternate means of communication, such as using hand signals or sign language, using picture symbols to communicate, or using electronic devices.
  • Occupational therapy helps people with autism do everyday tasks by finding ways to work within their needs and abilities.
  • Physical therapy includes activities and exercises that build motor skills and improve strength, posture, and balance.
  • Behavior management therapy, sometimes called applied behavior analysis, works by reinforcing wanted behaviors and reducing unwanted behaviors. It also suggests what caregivers can do before, during, after, and between episodes of problem behaviors.
  • Social skills training teaches children the skills they need to interact with others.
  • Cognitive behavior therapy helps people identify and change thoughts that lead to problem feelings or behaviors. Research shows it helps some people with autism deal with anxiety.
  • Joint attention therapy focuses on improving specific skills related to shared attention, such as pointing, showing, and coordinating looks between a person and an object. This is important for communication and language learning.

Early Intervention

Research shows that early diagnosis and interventions that occur at or before preschool age are more likely to have major long-term positive effects on symptoms and later skills. Early intervention programs help children gain the basic skills that they usually learn in the first 2 years of life, such as physical skills, thinking skills, communication skills, social skills, and emotional skills. Each state has its own early intervention program for children from birth to age 2 who are diagnosed with developmental delays or disabilities, including autism.

With early intervention, some children with autism make so much progress that they are no longer on the autism spectrum when they are older.

Educational Supports

Children with autism are guaranteed free, appropriate public education under the federal law known as the Individuals with Disabilities Education Improvement Act (IDEA). Special education teams in schools will work with families to design an Individualized Education Plan (IEP) for each child with autism, to list individualized goals, specify a plan for services, and list developmental specialists who will work with the child.

Medicine

Currently, there is no medicine that can cure autism or all of its symptoms. But some medicines can help treat certain symptoms associated with ASD, especially certain behaviors. A healthcare provider may prescribe medicine to treat specific ASD symptoms, including:

  • Aggression
  • Anxiety and depression
  • Attention
  • Hyperactivity
  • Irritability
  • Repetitive behavior
  • Self-injurious behavior

Medicines are sometimes used to help with challenging behaviors or co-occurring mental or physical health conditions. Two medicines (risperidone and aripripazol) are approved by the U.S. Food and Drug Administration (FDA) to treat irritability and aggression in autism. However, both drugs are associated with potential side effects such as drowsiness and weight gain.

Complementary Approaches

Many individuals with autism and their families use complementary health approaches. Often, they use these along with conventional medical care. Examples include animal-assisted therapy, arts therapies (music, art, drama, dance), acupuncture, massage therapy, yoga, and exercise-based therapies.

Some research suggests certain complementary approaches may help treat hypersensitivity, reduce anxiety, and improve social skills and mental health. However, further research is needed to establish beneficial outcomes from these approaches for individuals with autism. Always talk to your child’s healthcare provider before trying any complementary approach. Learn more about talking with your doctor about complementary health approaches.

Although some individuals and families may find that special diets improve their sense of well-being or health, research to date on the efficacy of dietary interventions in autism has had mixed results. Some people with ASD may have food selectivity that requires intervention to increase nutrition intake. Those who wish to try special diets should consult with their physician and have their overall nutritional needs evaluated before and while on the diet.

WARNING: There is no scientific evidence that secretin (a gastrointestinal hormone), hyperbaric oxygen, chelation therapies, or antifungal agents can help people with autism. These treatments may be dangerous.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on autism.

Find Treatment

Parents and caregivers can increase a child’s chance of improving speech and language skills by paying attention to language development early on. Children first develop pre-language skills before they begin to use words. These skills include using eye contact, gestures, body movements, imitation, and babbling.

If you have concerns about your child’s development, talk to their healthcare provider right away.

Working closely with healthcare and service providers is an important part of finding the right combination of supports. Here are some tips for families and caregivers:

  • Contact a healthcare provider, local health department, school, community center, or autism advocacy group to learn about special programs or local resources.
  • Find an autism support group. Sharing information and experiences can help people with autism and their caregivers learn about treatment options and autism-related programs.
  • Keep records of your conversations and meetings with healthcare providers and teachers. This information helps when it is time to decide which programs and services are appropriate.
  • Keep copies of healthcare reports and evaluations. This information may help people with autism qualify for special programs.

Find Support and Locate Mental Health Services with this SAMHSA resource.

Community Support

Here are some resources to help you find support:

If someone is experiencing an overdose, mental health crisis, or another emergency, call 911. Other emergency resources include:

  • 988 Suicide & Crisis Lifeline: If you or someone you know is struggling with or having thoughts of suicide, call or text 988 or chat at 988lifeline.org.
  • Substance Abuse and Mental Health Services Administration’s Disaster Distress Helpline: Call 1-800-985-5990 or text “talk with us” 24/7 on 66746.

Note: This resource list is for informational purposes only. It is not comprehensive, and an organization’s inclusion does not constitute an endorsement by NIH.  

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.  

NIH-funded researchers are working to:

  • Improve strategies for early screening and diagnosis. Tools for screening and diagnosis may include behavioral instruments, biomarkers, imaging methodologies, and others
  • Identify and characterize autism susceptibility genes
  • Understand the neuropathology of autism and autism-related behaviors
  • Detail the environmental variables that interact with genetic susceptibility factors to produce the autism phenotype
  • Determine how ASD symptoms and needs may change over time
  • Identify which therapies, services, and supports may benefit people with autism
  • Develop software to help people with autism who struggle with speech to communicate complex thoughts and interact more effectively in society
  • Find cost-effective ways to reduce the impact of conditions affecting speech, language, and social skills in children with increased likelihood for autism
  • Determine the types of services and supports that are most helpful for transition-age youth and adults with autism

NIH supports the Autism Centers of Excellence program. This is an NIH-wide initiative funding large-scale, multidisciplinary studies on autism.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.