What Is Autism?

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by differences in social communication, social interaction, and behavior. It is called a “spectrum” because the way autism presents varies widely from person to person: some individuals need substantial daily support, while others live largely independently. According to the CDC, 1 in 36 children in the United States has autism, making it one of the most common developmental diagnoses.

Autism is not a disease, and it is not caused by bad parenting or vaccines. It is a difference in how the brain is wired, with both challenges and strengths. Understanding what autism actually is, how it is identified, and what support looks like is essential for any family navigating a new or recent diagnosis.

How Common Is Autism?

The CDC’s most recent data from the Autism and Developmental Disabilities Monitoring (ADDM) Network, published in 2023, found that 1 in 36 8-year-olds in the U.S. has autism spectrum disorder. That represents a significant increase from 1 in 150 in 2000 and 1 in 44 in 2021.

Autism is 4 times more commonly diagnosed in boys than in girls, though research increasingly suggests that autism is underdiagnosed in females due to differences in how symptoms present and a tendency toward “masking” or camouflaging social difficulties. Autism occurs across all racial, ethnic, and socioeconomic groups.

Globally, the World Health Organization (WHO) estimates that approximately 1 in 100 children has autism, though methodologies vary significantly across countries. The higher U.S. prevalence reflects both improved diagnostic practices and broader diagnostic criteria.

What Are the Signs of Autism?

Autism signs appear differently by age, and many symptoms overlap with typical developmental variation in early childhood. That said, there are consistent patterns that clinicians and parents watch for.

Signs in infants and toddlers (under age 2)

Early signs are often subtle but meaningful:

• Doesn’t respond to their name by 12 months
• Doesn’t point to objects or wave by 12 months
• Limited eye contact, particularly during social interaction
• Doesn’t imitate facial expressions or actions
• No babbling or back-and-forth vocalizations by 12 months
• No single words by 16 months, or loss of previously acquired words
• Appears indifferent to other children or adults

Signs in preschool-age children (ages 2 to 5)

As language and social expectations increase, autism signs typically become more apparent:

• Difficulty playing with other children or preferring to play alone
• Unusual speech patterns such as echolalia (repeating phrases from TV or books)
• Intense, narrow interests that dominate their attention and play
• Insistence on routines with strong distress when routines change
• Repetitive motor movements: hand flapping, rocking, spinning
• Sensory sensitivities: covering ears, refusing certain food textures, extreme reactions to lights or touch

Signs in school-age children and adolescents

Social demands increase substantially in school, which often makes autism more noticeable in children who were less affected or better at masking early on:

• Difficulty making or keeping friends
• Misreading social cues, body language, or facial expressions
• Taking language very literally, missing sarcasm or humor
• Challenges with unstructured time like recess or lunch
• Emotional dysregulation, particularly during transitions or unexpected changes
• Anxiety, particularly in social situations

The American Academy of Pediatrics recommends routine autism screening tool at 18 months and 24 months, with additional evaluation whenever a parent, teacher, or clinician has concerns. If you have concerns about your child, do not wait for a formal diagnosis to start asking questions. Visit our autism screening page to learn more.

What Causes Autism?

Autism does not have a single cause. Research points to a complex combination of genetic and environmental factors, with genetics playing the largest role.

Genetic factors

Twin studies show that if one identical twin has autism, the other has it 60 to 90% of the time. For non-identical twins, the rate is 30 to 40%. This points strongly to genetic contribution. Researchers have identified over 1,000 genes associated with autism risk, though no single gene explains most cases. Autism is typically polygenic, meaning many genes each contribute a small amount of risk.

Environmental factors

Certain prenatal and perinatal conditions appear to increase autism risk, including advanced parental age, gestational diabetes, premature birth, and prenatal exposure to certain medications (particularly valproate). These are correlational factors, not direct causes, and most children with these risk factors do not develop autism.

What does not cause autism

Vaccines do not cause autism. This claim originated from a fraudulent 1998 study that was retracted and whose author lost his medical license. Dozens of large, methodologically rigorous studies involving millions of children have found no connection between any vaccine and autism. The CDC, NIH, WHO, and American Academy of Pediatrics all confirm this.

How Is Autism Diagnosed?

Autism is diagnosed through clinical evaluation, not a blood test or brain scan. There is no biological marker. Diagnosis relies on structured observation of behavior, developmental history, and standardized assessment tools compared against DSM-5-TR criteria.

A comprehensive autism evaluation typically includes:

• Parent interview about developmental history, current behaviors, and family history
• Direct observation and standardized tools like the ADOS-2 (Autism Diagnostic Observation Schedule)
• Cognitive and adaptive behavior assessments
• Speech-language evaluation
• Ruling out other conditions with similar presentations

Evaluations are conducted by developmental pediatricians, child psychologists, neuropsychologists, or multidisciplinary autism evaluation teams. The median age of diagnosis in the U.S. is 4 to 5 years old, but symptoms are often noticeable much earlier. Early diagnosis enables earlier intervention, which research strongly supports.

What Is the Autism Spectrum?

The concept of a “spectrum” reflects that autism presents differently in different people. Two children with the same diagnosis can look completely different. One child may be non-speaking with high support needs. Another may be a verbal, academically capable teenager who struggles primarily with social anxiety and rigid thinking.

The DSM-5-TR describes three support levels. Level 1 means requiring support. Level 2 means requiring substantial support. Level 3 means requiring very substantial support. These levels apply to social communication and to restricted and repetitive behaviors separately, because a person’s needs can differ across those two domains.

The term “high-functioning autism” was commonly used to describe Level 1 presentations, but it is no longer an official diagnostic category and is considered somewhat misleading. A person who appears high-functioning can still struggle significantly, particularly with anxiety, sensory processing, and social exhaustion. All autistic people deserve access to appropriate support, regardless of where on the spectrum they fall.

What Are the Treatment Options for Autism?

There is no “cure” for autism, and most autistic self-advocates do not want one. What treatment means in practice is providing the supports and interventions that allow each person to develop their fullest potential and lead a meaningful life.

Applied Behavior Analysis (ABA) therapy

ABA is the most extensively researched intervention for autism, with over 1,000 peer-reviewed studies supporting its effectiveness. The U.S. Surgeon General and the American Academy of Pediatrics both endorse it as an evidence-based treatment. ABA targets communication, social skills, daily living skills, and behavior management through systematic instruction, positive reinforcement, and data-driven program adjustments.

Modern ABA is person-centered, meaning it is built around your child’s individual goals and delivered in ways that respect their preferences and dignity. Center-based ABA and in-home ABA are both effective options depending on your child’s needs and your family’s schedule.

Speech-language therapy

Speech therapy targets receptive and expressive language, pragmatic social communication, and, for non-speaking children, augmentative and alternative communication (AAC). It is often delivered alongside ABA for maximum impact on communication outcomes.

Occupational therapy

OT addresses sensory processing, fine motor skills, daily living tasks, and school-related functional skills. Sensory integration therapy is a common OT approach for children with significant sensory sensitivities.

Social skills groups

Structured peer interaction programs help autistic children and adolescents practice social skills in low-stakes, supportive settings. Research supports these programs for individuals with higher language abilities.

Medication

There are no FDA-approved medications for core autism symptoms. However, medications may be prescribed to treat co-occurring conditions like ADHD, anxiety, depression, or epilepsy, which affect a significant portion of autistic individuals.

What Is High Functioning Autism?

High functioning autism (HFA) is an informal term used to describe individuals who have autism but who are able to communicate and interact at a higher level. They may attend school, have friendships, and hold jobs. Despite their ability to manage daily life, people with HFA may still need support for sensory sensitivities, social anxiety, emotional regulation, and communication in complex social situations.

Remember that “high-functioning” does not mean “does not need support.” Everyone with autism spectrum disorder has unique needs and deserves individualized care.

What Does Life Look Like for Autistic People?

The answer varies as much as autistic people themselves do. Many autistic adults live independently, have careers, form close relationships, and make meaningful contributions to their communities and fields. Many also continue to need support throughout their lives, whether with daily living tasks, navigating social environments, or managing sensory challenges in the workplace.

What research consistently shows is that early intervention, access to appropriate supports, and environments that understand and accommodate autism lead to better outcomes across all measures: quality of life, employment, relationships, and independence. A diagnosis is not a ceiling. It is a starting point.

How Can Treetop Help?

Treetop provides evidence-based ABA therapy across 11 states, serving children from toddlers through adolescence. Every program starts with a comprehensive assessment by a Board Certified Behavior Analyst. Goals are individualized, progress is data-tracked at every session, and parents are active participants throughout.

Most families start within 2 weeks of their first contact, and 79% pay $0 out-of-pocket. If your child has just been diagnosed, or if you have concerns and want to understand your options, reach out to our team. We can answer your questions and walk you through what the right next step looks like for your child.

Frequently Asked Questions

Is autism a disability?

Legally, autism qualifies as a disability under the Americans with Disabilities Act, the Individuals with Disabilities Education Act, and the Social Security Act, which means individuals and families are entitled to specific protections, services, and accommodations. Many autistic people also identify with disability as a meaningful part of their identity, while others do not. Both perspectives are valid.

Can autism be detected before birth?

Not reliably. There is no prenatal test for autism. Research is exploring genetic screening approaches, but autism is polygenic and complex, making prenatal prediction extremely difficult. The earliest reliable detection typically happens around 18 to 24 months through developmental screening.

Do autistic children have special abilities?

Some do, and some do not. The “savant” stereotype (extraordinary abilities in one area) applies to a minority of autistic individuals. What is more broadly true is that many autistic people have intense focus and depth of knowledge in their areas of interest, strong attention to detail, and high integrity. These are genuine strengths that show up in many autistic people without meeting the dramatic savant standard.

Can autism be treated with diet?

No dietary intervention has been shown to treat autism itself. Some families report behavioral improvements with gluten-free or casein-free diets, but controlled research has not supported these claims reliably. Some autistic children have co-occurring gastrointestinal issues that warrant dietary attention for GI health, but these are separate from ASD treatment.

Is autism more common now than it used to be?

Prevalence estimates have risen significantly, but much of this reflects broader diagnostic criteria, increased awareness, improved screening, and reduced stigma around seeking evaluation. It is likely that some real increase in prevalence exists, but researchers debate the extent to which it reflects a true biological increase versus better identification.

When should I start looking for ABA therapy after a diagnosis?

Immediately. ABA waitlists can be 3 to 6 months or longer in some areas. Contact ABA providers the same week you receive a diagnosis. At Treetop, we aim to get families started within 2 weeks of intake. The sooner intervention begins, the better the long-term outcomes. See what to expect when starting, or contact us today.