What Is Autism?

Medically Reviewed by Dan Brennan, MD on September 02, 2023
13 min read

Autism, also called autism spectrum disorder (ASD), is a complicated, lifelong condition that includes problems with communication and behavior. It's a spectrum disorder, which means it affects people in different ways and in varying degrees. It usually appears by age 2 or 3. 

People with autism have trouble with communication. They have trouble understanding what other people think and feel. This makes it hard for them to express themselves, either with words or through gestures, facial expressions, and touch.

People with autism may have problems with learning. Their skills might develop unevenly. For example, they could have trouble communicating but be unusually good at art, music, math, or things that involve memory. Because of this, they might do especially well on tests of analysis or problem-solving.

More children are diagnosed with autism now than ever before. But the latest numbers could be higher because of changes in how it’s diagnosed, not because more children have the disorder.

"Low-functioning" vs. "high-functioning" autism 

Every person with autism will be affected differently. Some people have a more challenging time with social, learning, or communication abilities. They may need help with everyday tasks and in some cases aren't able to live alone. Many people call this "low-functioning autism."

Other people may have autism with less obvious symptoms. They often do well and school and have fewer problems communicating. People usually call this "high-functioning autism."

But the terms "high-functioning" and "low-functioning" can be offensive. It's best to avoid them. To talk about how autism affects someone, you can instead use terms like "more significant" or "less significant."

Symptoms of autism usually appear before a child turns 3. Some people show signs from birth.

Common symptoms of autism include:

  • A lack of eye contact
  • A narrow range of interests or intense interest in certain topics
  • Doing something over and over, like repeating words or phrases, rocking back and forth, or fidgeting with objects (such as flipping a light switch)
  • High sensitivity to sounds, touches, smells, or sights that seem ordinary to other people
  • Not looking at or listening to other people
  • Not looking at things when another person points at you
  • Not wanting to be held or cuddled
  • Problems understanding or using speech, gestures, facial expressions, or tone of voice
  • Talking in a sing-song, flat, or robotic voice
  • Trouble adapting to changes in routine

Some children with autism may also have seizures. These might not start until adolescence.

Autism symptoms in adults

In adults, autism may show up in specific ways. Common symptoms can include:

  • Trouble understanding what other people are thinking or feeling
  • Choosing to be on your own or having a hard time making friends
  • Anxiety about social activities
  • Keeping a daily routine and getting upset if it changes
  • Having a hard time expressing how you feel
  • Taking things literally or not understanding sarcasm
  • Coming off as blunt, uninterested, or rude to others without meaning to

Other signs of autism in adults could include:

  • Avoiding eye contact
  • Not understanding social queues or "rules"
  • Getting too close to others or getting upset if someone gets too close or touches you
  • Being very interested in specific things
  • Picking up on small details, smells, sounds, or patterns that other people don't
  • Wanting to plan things very carefully before doing them

Autism symptoms in children

Children may show different signs of autism. They may include:

  • Not responding to their name by 9 months old
  • Not showing facial expressions by 9 months old
  • Not wanting to play simple games (like pat-a-cake) by 12 months old
  • Doesn't use gestures (like waving hello) by 12 months old
  • Doesn't understand when other people are sad or mad by 24 month old
  • Doesn't notice or want to join other children to play by 36 months old
  • Doesn't sing, act, or dance for you by 60 months old
  • Lines up toys in a specific order and gets upset if the order is changed 
  • Shows obsessive interests
  • Rocks their body, flaps their hands, or spins in circles
  • Delayed language, movement, learning, or cognitive skills
  • Odd sleeping or eating habits
  • Less or more fear toward things than would ordinarily be expected


Stimming is a self-stimulating behavior, such as hand and arm flapping, rocking, spinning, twirling, jumping, head-banging, or other similar body movements. It can also include using an object over and over again, like flicking a rubber band, twirling a string, touching something with a certain texture, and more.

People with autism may stim for fun, to ease boredom, or to cope with stress or anxiety. It can also help them adjust the level of sensory input. For example, they may twirl a string so they can watch it or focus on one sound so they can tune out another loud or stressful noise. 


At times, a person with autism may become overwhelmed by a situation and be unable to find a way to respond. This can cause them to have a meltdown. They may cry, scream, or act out physically by kicking, punching, or biting. They may shut down completely and stop responding in any way. This isn't a tantrum: They're simply unable to deal with being overwhelmed or to explain their feelings. 

These types were once thought to be separate conditions. Now, they fall under the range of autism spectrum disorders including:

  • Asperger's syndrome. Children with Asperger's syndrome tend to score in the average or above-average range on intelligence tests. But they may have challenges with social skills and show a narrow scope of interests.
  • Autistic disorder. This is what most people think of when they hear the word "autism." It affects social interactions, communication, and play in children younger than 3 years.
  • Childhood disintegrative disorder. Children with this disorder have typical development for at least 2 years and then lose some or most of their communication and social skills.
  • Pervasive developmental disorder (PDD or atypical autism). Your doctor might use this term if your child has some autistic behavior, like delays in social and communications skills, but doesn’t fit into another category.

Exactly why autism happens isn't clear. It could stem from problems in parts of your brain that interpret sensory input and process language.

Autism is four times more common in boys than in girls. It can happen in people of any race, ethnicity, or social background. Family income, lifestyle, or educational level doesn’t affect a child’s risk of autism. But there are some risk factors:

  • A child with an older parent has a higher risk of autism.
  • Pregnant women who are exposed to certain drugs or chemicals, like alcohol or anti-seizure medications, are more likely to have autistic children. Other risk factors include maternal metabolic conditions such as diabetes and obesity. Research has also linked autism to untreated phenylketonuria (also called PKU, a metabolic disorder caused by the absence of an enzyme) and rubella (German measles).

Is autism genetic?

Autism runs in families, so certain combinations of genes may increase a child’s risk. Changes in more than 1,000 genes may be linked to autism. But not all of them are confirmed by experts. Genetic factors can affect someone's risk of autism anywhere from 40 to 80%.

Your overall risk depends on the combination of your genes, environment, your parents' age, and any birth complications.

A rare gene mutation or chromosome issue is likely to be the sole cause of about 2% to 4% of people with autism. This tends to happen in conditions that also affect other parts of the body, like with mutations in the ADNP gene. With ADNP syndrome, a person will show signs of autism as well as have specific facial features. 

Many of the genes that are involved in autism are related to brain development. This may be why autism symptoms tend to involve issues with communication, cognitive functioning, or socialization.

Vaccines and autism

Vaccines don't cause autism. Even though some people have concerns that they do, studies have shown that there is no link between the two. Experts have reviewed the safety of eight vaccines for children and adults. They found that they're very safe, despite rare exceptions. Other studies have looked at the ingredients of different vaccines and found no link to autism. The health benefits of vaccines in preventing diseases far outweigh any potential risks. 

It can be hard to get a definite diagnosis of autism. Your doctor will focus on behavior and development.

For children, diagnosis usually takes two steps.

  • A developmental screening will tell your doctor whether your child is on track with basic skills like learning, speaking, behavior, and moving. Experts suggest that children be screened for these developmental delays during their regular checkups at 9 months, 18 months, and 24 or 30 months of age. Children are routinely checked specifically for autism at their 18-month and 24-month checkups.
  • If your child shows signs of a problem on these screenings, they’ll need a more complete evaluation. This might include hearing and vision tests or genetic tests. Your doctor might want to bring in someone who specializes in autism disorders, like a developmental pediatrician or a child psychologist. Some psychologists can also give a test called the Autism Diagnostic Observation Schedule (ADOS).

If you weren’t diagnosed with autism as a child but notice yourself showing symptoms, talk to your doctor.

If you've just gotten a diagnosis

If you just got an autism diagnosis, there are a few steps you can take to feel your best:

Take the time you need to understand the diagnosis. You might feel a ranged of emotions. Know that you can reach out to your doctor for help. You can continue a normal life even after a diagnosis.

Do your research. You can read up on articles (such as this one) about autism. There's a lot of information out there, but a few good sources are all you need to start learning about your diagnosis.

Listen to others with autism. There are many blogs, books, or videos that you can use to understand the condition. People with autism can also share their stories to help you learn more about it.

Get the help you need. If you feel alone after you or your child got an autism diagnosis, look for support. National advocacy groups, support groups, your doctor, people on social media with autism, or your school, job, or college can help you navigate a diagnosis.

Keep an eye out for other health issues. While autism isn't an illness, many people with autism might also have other conditions, including ADHD, dyslexia, and others. If you have questions about you or your child's health, see your doctor and explain your concerns.

If you have autism, you’ll have it your entire life. But early treatment can make a big difference in development for a child with autism. If you think your child shows symptoms of ASD, tell your doctor as soon as possible.

Autism treatments

What works for one person might not work for another. Your doctor should tailor treatment for you or your child. The main types of treatments are:

  • Behavioral: Helps a person understand the causes and results of behaviors so they can change unwanted behaviors.  
  • Developmental: Speech therapy improves communication skills, physical therapy improves motor ability, occupational therapy works on life skills like dressing and eating. 
  • Psychological: Treatments like cognitive-behavioral therapy (CBT) can help people deal with anxiety, depression, or other mental health issues In addition to autism.
  • Educational: Adapts learning processes to the needs of people with autism.
  • Social-relational: Focuses on bettering social skills and building emotional bonds.
  • Medications: Work to ease symptoms of ASD, like attention problems, hyperactivity, or anxiety.

Complementary treatments may help boost learning and communication skills in some people with autism. Complementary therapies include music, art, or animal-assisted therapy, such as horseback riding.

Applied behavior analysis (ABA) is a type of treatment that aims to promote positive behavior and discourage negative  or harmful behavior. Some experts believe that ABA is a form of behavior control. They say that it forces people to conform to a rigid definition of "normal" and stifles behavior that's part of having autism. Advocates say that ABA has evolved from this approach. They claim that it's the best way for a person with autism to adapt in a way that lets them live in society more easily. 

Fake autism treatments

There are certain treatments that are sold or advertised to treat autism but don't actually work. Some of these fake treatments can even be dangerous. Don't try any of the following for autism:

  • Raw camel's milk
  • GcMAF, which is an unlicensed injection made from blood cells
  • CEASE, which tells people to avoid vaccinations and suggests people take nutritional supplements that could be dangerous
  • Chlorine dioxide (CD) or Mineral Miracle Solution (MMS)
  • Some vitamins, minerals, and supplements
  • Secretin, a hormone found in your body
  • Chelation, which takes out heavy metal toxins in your blood

To spot a fake treatment, look for these warning signs:

  • Claims that it's a "cure," "miracle," or that you can "recover from" autism.
  • It's not available on major, reputable health sites.
  • It costs a lot of money.
  • It claims to work in many people "instantly."
  • Personal stories that it's worked instead of medical data.
  • States that anyone can do it, even without medical training.
  • It claims to cure lots of conditions.

Some groups of people are affected differently by autism.

Autism in women

Autism can sometimes be different for women compared to men. Compared to men, autistic cisgender women might:

  • Hide their feelings
  • Be quieter
  • Copy people who don't have autism or hide their autism signs in order to "fit in"
  • Seem to deal better with social situations
  • Show fewer signs of repetitive behaviors

Your doctor may not have as much knowledge about diagnosing girls or women with autism. Since many symptoms are focused on male stereotypes of autism, this can make it harder to tell if a female has autism. Because of this, girls and women with autism may be misdiagnosed or missed entirely. As experts become more aware of this, the estimates of how many men have autism compared to women has gotten smaller. 

Autism and Racial and Ethnic Differences

More white children are diagnosed with autism spectrum disorder compared to Black or Hispanic children. Some of the reasons that these groups may not be getting diagnosis or care include: 

  • Stigma about the disorder 
  • Less access to medical resources because of non-citizenship or income
  • Not speaking English as a primary language

LGBTQIA+ and Autism

Research shows that people with autism are more likely to identify as a part of the LGBTQIA+ community than people who don't have it. People in this group who also have autism are more likely to face discrimination, issues with getting medical care, violence, and cultural stigmas. This can create greater mental health complications for LGBTQIA+ individuals who are autistic and already at a higher risk for these complications.

Talk to your doctor before trying something different, like a special diet. There’s no hard evidence that special diets help children with ASD. Autism is a complex brain disorder. 

Some children with autism might appear to be picky eaters. They may only eat foods of a certain color or texture, not eat enough or eat too much, or eat things that aren't food. They can have constipation, which makes them feel full even if they're not, or have issues with coughing or choking while they eat.

While it may seem that cutting out certain foods could relieve your child’s symptoms, it might actually cause more harm.

For example, children with autism often have thinner bones. Dairy products have nutrients that can make their bones stronger. Studies on a protein in milk products called casein have found that many children performed the same whether or not they ate foods with this protein. Their autism symptoms didn’t change in any remarkable way.

Some evidence shows that people with autism may have low levels of certain vitamins and minerals. This does not cause autism spectrum disorder. But your doctor may suggest supplements to improve nutrition. Vitamin B and magnesium are two of the supplements most often used for people with autism. But people can overdose on these vitamins, so megavitamins should be avoided.

However, some diet changes may help with certain symptoms of autism. Food allergies, for example, may make behavior problems worse. Removing the allergen from your child's diet may make some behavior issues better.

The important thing is that your child’s diet needs to support their specific nutritional needs and ASD symptoms. The best way to settle on the most useful diet is to work with your doctor and a nutrition specialist like a registered dietitian. They’ll help you design a meal plan tailored for your child.

Some children with autism have digestive problems like constipation, belly pain, or nausea and vomiting. Your doctor can suggest a diet that won’t make these issues worse.

And remember, nutritional needs change over time. Your child’s dietitian will help you make sure the foods they eat are still meeting their needs as they get older.


You can help your child communicate better with autism by:

  • Using their name so they know you're speaking to them
  • Speaking slowly and clearly
  • Keeping language clear and simple
  • Give them extra time to understand what you've just said
  • Use simple gestures, pictures, or eye contact to help them understand what you're saying


  • Having a conversation in a noisy or crowded area
  • Saying things that have more than one meaning like "break a leg"
  • Asking your child a lot of questions

Trouble sleeping

Many kids with autism have a hard time falling asleep or staying asleep. You can help them by:

  • Keeping a sleep diary to look for common issues
  • Following the same bedtime routine each night
  • Letting them use ear plugs to sleep, if they help
  • Keeping their bedroom dark and quiet
  • Talking to a doctor about issues that might affect their sleep


To help your child make friends and socialize:

  • Ask your child's school if they can help.
  • Ask your autism care team if they can give tips.
  • Look into the National Autism Society directory for local social groups that can help those with autism.
  • Ask for or read information from other parents of children who have autism.

Make sure you don't:

  • Force your kid into social settings if they want to be on their own instead.
  • Put pressure on your child. Give them time to learn social skills.