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Autism spectrum disorder: Signs, symptoms, and scope

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Outline of a face on a chalkboard with Autism Awareness ribbon

What Is Autism?

Autism refers to autism spectrum disorder (ASD), a group of developmental disorders encompassing social and communication challenges as well as repetitive behaviors.

An autism diagnosis can occur at any age, although most diagnoses occur in childhood. According to the Centers for Disease Control and Prevention (CDC), a medical doctor can reliably diagnose a child as young as two years old.

What Does It Mean to Be “On the Spectrum”?

When discussing autism, you may have heard the term “on the spectrum” used before. This is because autism spectrum disorder encompasses a range of developmental disorders.

The autism spectrum ranges from mild to severe and encompasses different subtypes of autism with different symptoms, strengths, and struggles. Disorders like Asperger’s syndrome, autistic disorder, and pervasive developmental disorder not otherwise specified (PDD-NOS) were once considered separate disorders. Today, they are all part of ASD.

You may have heard terms like “high-functioning autism” and “low-functioning autism,” which were once used to refer to the wide range of this spectrum. However, these words are not medical terms and have since fallen out of use. Today, the term “autism spectrum disorder” is used for all subtypes of autism, regardless of severity.

Symptoms of Autism

Signs of Autism in Children

The CDC estimates that one in every 54 children in the United States has ASD. Most children with ASD receive a diagnosis by age eight. While autism affects people of every demographic, boys are four times more likely to be diagnosed with ASD than girls.

Signs of autism in children occur early, often by the age of two. Since ASD is a developmental disorder, it’s important to monitor your baby’s development and to watch for any missed milestones. Symptoms of autism in children include:

    • Avoiding eye contact
    • Disliking being held or cuddled
    • Not responding to people when spoken to, but still hearing and responding to other noises
    • Repeating words, phrases, or actions
    • Not playing “pretend”
    • Learning skills and then losing them
    • Struggling with changes to their routine

Adult Autism

Some people don’t receive a diagnosis of autism until adulthood. They may have received a different or less accurate diagnosis as a child, or they may have never received a diagnosis of any sort.

The difficulty in diagnosing autism in adults is that ASD is a developmental disorder. Children with autism miss developmental milestones or arrive at them later than usual. Adults can’t be monitored for developmental abnormalities because those milestones were reached or missed long ago.

Additionally, some symptoms of autism in adults can overlap with symptoms of certain mental health disorders, such as anxiety or ADHD. It’s especially important not to rely on self-diagnosis for ASD because the symptoms of adult autism can be so difficult to separate from other conditions. Trust a doctor or therapist to offer you a professional diagnosis.

Symptoms of autism in adults include:

    • Missing social cues
    • Avoiding eye contact
    • Difficulty reading body language
    • Misunderstanding figures of speech
    • Struggling with changes to routine
    • Feeling overstimulated
    • Deeply studying one or two topics or skills
    • Engaging in repetitive, self-stimulating habits (stimming)

What Is Stimming?

Stimming is the act of engaging in a repetitive, self-stimulating behavior as a way of self-soothing or expressing stressful emotions. Common forms of stimming include biting your nails, drumming your fingers on a table, or jiggling your foot while seated.

Everyone engages in some form of stimming at some point in their life. You may bite your lips during a test, pace around before a presentation, or twirl your hair during a first date.

For people with autism, stimming behaviors may be more obvious, or they may be more difficult to control. Common stimming behaviors for those with autism include rocking, bouncing, rubbing, scratching, staring, snapping their fingers, or repeating certain words or phrases.

Autism Diagnosis

What Causes Autism?

Although there is no identified single cause for ASD, there are certain risk factors that may make your child more likely to develop autism:

    • Genetics: According to the CDC, you’re more likely to develop ASD if you have an older sibling who has ASD. Additionally, there are certain other genetic or chromosomal syndromes that may increase your likelihood for autism.
    • Pregnancy: Research suggests that certain drugs taken during pregnancy may result in a higher risk for ASD. Additionally, your child is more likely to develop autism if you are pregnant with them later in life (also known as a geriatric pregnancy).

Despite some public misinformation that has circulated over the years, numerous scientific studies have shown that there is no causal link between vaccines and autism.

Who Can Diagnose Autism?

If you have questions about your child’s development, you should first see a pediatrician. Your child’s doctor can answer your questions and conduct some tests to rule out other explanations for your concerns.

If your pediatrician believes an autism diagnosis may be likely, they will then refer you to an autism specialist. An autism specialist has the necessary training and certifications to offer a professional diagnosis for your child.

If you are wondering if you may have autism as an adult, you should first set an appointment with your primary care physician (PCP). They can address your concerns and help you rule out other health problems that may present similar symptoms.

Your doctor will then likely refer you to a psychologist or psychiatrist for a professional evaluation. Click here to find therapists who specialize in adult autism near you.

Treatment for Autism

Early Intervention

There is no cure for autism. However, early treatment is correlated with better outcomes. Your child can receive early intervention treatment before the age of three to help them learn certain skills, such as walking, talking, and social interaction. Common therapies for children with autism include:

    • Applied behavioral analysis
    • Social skills training
    • DIRFloortime®
    • Pivotal Response Treatment® (PRT)

Your child may also receive additional services, like occupational therapy or speech therapy, before they receive an official ASD diagnosis. If you suspect your child may have autism, it’s important to seek treatment right away so they can take advantage of these early intervention treatments.


Medication for autism is typically only prescribed for older children or adults. Although medicine cannot cure autism, it may lessen some of the symptoms. Medication can be particularly useful for people with autism who have severe symptoms that interfere with their daily lives.

Psychotherapy for Adults

Starting therapy early for children with autism can lead to more positive outcomes. However, therapy can still be a great resource for older children as well as adults.

An autism diagnosis in adulthood can have a big impact on a person’s sense of identity. A therapist can help an adult with autism process their diagnosis in a healthy way. They can also help adults resolve past issues or traumas that may be better understood in light of this new diagnosis. Additionally, adults with autism may struggle with mental health disorders, such as anxiety or depression, and therapy can help address these concerns.

Autism and Identity

Autism is a developmental disorder that will affect a person for the rest of their life. In some cases, it may qualify as a legal disability.

Because autism is not an illness to be overcome, some people with autism view it as an identity to be embraced. This affects the way people talk about autism.

How to Talk About Autism

When people talk about autism, it is important to consider the lived experiences of people with ASD and to follow their lead on how they wish to discuss autism. Whether they consider autism to be a condition, disability, identity, or a mix of all three, their perspectives matter.

Some people are proud to have autism and prefer to be called an “autistic person.” Others want to separate their identity from their diagnosis and prefer to use terms like “person with autism.”

Additionally, some people in the autistic community have embraced the term “neurodivergent” to emphasize that their condition simply makes them different, not worse or less than others who are not autistic (also known as “neurotypical”). The term “neurodivergent” has also been used by people with other developmental or mental health disorders besides autism.

People with autism have different experiences and may view their diagnosis differently. It’s important to use language that respects people with autism as a whole while also honoring the specific preferences of the person with ASD. As Dr. Stephen Shore famously said, “If you’ve met one person with autism, you’ve met one person with autism.”

If you are the parent of a child with autism, be careful not to discuss autism in a way that makes autism an “enemy” or “illness” or causes shame for the child. If your child is old enough, start a conversation with them about how they view their diagnosis and how they want to discuss it.

Treatment and Acceptance

Acceptance and even pride in an autism diagnosis are not at odds with seeking treatment.

Parents should be encouraged to seek early treatment interventions for their child with autism in an effort to secure the most positive outcomes. However, it is also equally important to caution parents not to prioritize “curing” their child of autism or making them “normal.” Autism cannot be cured, and children with autism can lead full lives without striving to be “normal.”

At the same time, it’s okay to feel frustrated with the lived realities of autism, whether you have autism yourself or you are the parent of a child with autism. Remember that people with autism have strengths, weaknesses, opportunities, and challenges, just like people without autism.

Frequently Asked Questions (FAQs)

“Do Vaccines Cause Autism?” No.

Vaccines do not cause autism. Multiple studies have proven no link between vaccines (or their isolated ingredients) and autism. In fact, the original study that claimed to find this non-existent connection was based on fraudulent data and was later retracted.

“Why Do So Many Children Today Have Autism?”

The term “autism” was first used as early as 1908, but its definition has changed greatly over the past 100 years or so. What has remained true is that developmental disorders like autism have existed for centuries, even if they went unnamed or undefined.

This means that, historically, many people who we would likely diagnose with autism under today’s standards went undiagnosed or misdiagnosed in the past. As awareness of autism increases, rates of diagnosis will also increase. This doesn’t necessarily mean that there are more people with autism in the world. Instead, it means that more people with autism are actually getting diagnosed.

About the author

The editorial team at works with the world’s leading clinical experts to bring you accessible, insightful information about mental health topics and trends.

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