Autism

Autism is a lifelong difference in how a person's brain develops. It shapes how a person communicates, connects with other people and takes in the world through the senses. It is not an illness.^1,3

Many people think of autism as a childhood topic. But autistic children grow up to be autistic adults, and some people only learn they are autistic in midlife or later. This page gives the big picture and links to each topic.

What is autism?

The medical name is autism spectrum disorder, or ASD. "Spectrum" means that autism looks different from one person to the next. It is not a line from "a little autistic" to "very autistic."^1,3

Doctors look for two main things:^1,4

• Differences in social communication. For example, eye contact may feel hard or uncomfortable. A person may find small talk or unwritten social rules confusing. Some autistic people speak a lot, some speak little, and some do not speak but communicate in other ways.
• Repeated behaviors, strong interests and sensory differences. A person may like steady routines and get upset when plans change. They may have deep knowledge of a favorite subject, repeat movements such as rocking or hand flapping, or react strongly to sounds, smells, tastes, light or textures.

Autism also comes with strengths. Many autistic people notice fine details, learn a subject in great depth, or do very well in fields such as math, science, music or art.¹

Autism usually starts to show in early childhood, because it begins with how the brain develops. Researchers do not know all the causes. Genes and the environment may both play a part.¹

How common is autism?

In the most recent CDC study, about 1 in 31 eight-year-olds in 16 U.S. communities was identified as autistic in 2022.⁷ Boys were identified about 3.4 times as often as girls. That gap may partly reflect that girls and women are often missed.^7,10

Counting adults is harder, because no U.S. system tracks them. A CDC model estimated that about 2.2% of U.S. adults, around 1 in 45, were autistic in 2017. That was about 5.4 million people. This is an estimate, not a head count.⁶

Researchers also found that about 4 in 10 of the 8-year-olds with enough testing data had an intellectual disability.⁷ So the autism community includes people with very different needs.

Words that show respect

Language matters to many autistic people.

• Many adults prefer "autistic person." They see autism as part of who they are. Others prefer "person with autism." If you are not sure, ask what the person likes.
• Neurodiversity is the idea that human brains work in many ways, and that these differences are part of normal human variety. Neurodivergent is a word some people use for a brain that works differently, such as an autistic or ADHD brain.
• Try not to say "high-functioning" or "low-functioning." These labels hide both strengths and struggles. It is kinder and clearer to talk about support needs, such as "needs help with daily tasks" or "needs a quiet workplace."
• Avoid describing autism as a disease, a tragedy or something to "fix."

Autism in adults

Most adults who learn they are autistic have been autistic all their lives. They may have felt "different" for years without knowing why. Some were told they were shy, anxious or "difficult" instead.

Some people are diagnosed late because their signs are less obvious or because they learned to mask (also called camouflage). Masking means hiding autistic traits to fit in, such as forcing eye contact or copying how others talk. One survey of 502 autistic adults found that women reported more masking than men, and adults diagnosed later in life reported more of it than those diagnosed as children.¹⁰

Masking can be tiring. Autistic adults have also described autistic burnout, a deep, long-lasting exhaustion that can come with a loss of skills and less tolerance for noise and other input. It often follows years of stress and too little support. The research is early, but the people who took part said it was different from ordinary job burnout or depression.⁹

Autism can look like other conditions, and the signs can overlap with anxiety or ADHD.¹ Learn more in signs of autism in adults and getting an autism diagnosis as an adult.

Other health needs that often go along with autism

Many autistic people also have other health needs. Common ones include anxiety, ADHD, seizures, sleep problems and stomach problems such as constipation.⁴ Depression and low mood can also occur.⁵ These are real health problems that deserve care. They are not "just part of autism."

Mental health care works best when the clinician understands autism. See autism and other health conditions, and our pages on anxiety, depression, ADHD and sleep.

What kinds of support help?

Support aims to make daily life easier and healthier. It does not aim to make a person "act less autistic."⁵ A good plan fits the person and may include several of these:⁵

Read more in support and therapy for autism and daily life, work and autistic burnout.

Autism in later life

Older adults can be autistic too. Some people are not diagnosed until adulthood, including later life.³ Some find out only after years of trouble that no one could explain. A late diagnosis can bring relief and a new way to understand one's life story.

As people age, changes in routine, moving to a care setting, or losing a spouse can be especially hard for autistic adults. Autism can sometimes be mistaken for dementia, and dementia can be mistaken for autism. A doctor who knows both can help tell them apart. Learn more in autism in later life, our older adults section and the dementia guide.

Supporting an autistic family member

The most helpful thing you can do is to try to understand rather than change. Learn what overloads the person and what calms them. Say things plainly, and give extra time when plans change. Take care of yourself too. Read supporting an autistic family member and caregiver support.

All autism topics

• Signs of autism in adults
• Getting an autism diagnosis as an adult
• Autism and other health conditions
• Support and therapy
• Daily life, work and autistic burnout
• Supporting an autistic family member
• Autism in later life

In this section

When to get help

Consider seeing a doctor if you think you may be autistic, or if life feels harder than it should because of noise, change, people or exhaustion. A primary care doctor is a good first step. Adults can ask for a referral to a psychologist, psychiatrist or neuropsychologist who has experience with autism.¹ You can also take our mental health check-in.

Education only. This page is general information written from the sources listed. It is not medical, legal or financial advice and does not replace a doctor, therapist or lawyer who knows your situation. How we write and check pages.