Autism Facts and Statistics: What You Need to Know

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Autism spectrum disorder is a developmental disability. Autism prevalence has grown rapidly over the last few decades. Today, approximately 1 in every 44 children is diagnosed with autism. Boys are 4 times more likely than girls to receive an autism diagnosis.

Autism is a lifelong neurological and developmental disorder that starts in childhood. People with autism have problems with social communication and behavior. Some people with autism have very severe challenges while others have relatively mild symptoms. The number of people with autism has risen rapidly over the last 30 years.

This article will highlight important facts and statistics you should know about autism spectrum disorder.

Boy with autism looking out window

Juanmonino / Getty Images

Autism Overview

Autism is a developmental disorder that impacts social and communication skills, behavior, and responses to sensory input. It is a spectrum disorder, which means that autistic symptoms can be relatively mild or very severe. Autism, by definition, starts in early childhood or even infancy, though it may be diagnosed later in life.

Changing Autism Criteria

The diagnostic criteria have changed radically over the past few decades. At one point it was described as a severe and unusual disorder.

Later it was described as a spectrum disorder under which various diagnoses fell, including the milder Asperger's syndrome and a catchall diagnosis called pervasive developmental disorder not otherwise specified (PDD-NOS). Today, people with milder and more severe forms of autism are all diagnosed as having autism spectrum disorder.

How Common Is Autism?

In 2021, 1 in 44 8-year-old children were diagnosed with autism. This prevalence has increased radically since the turn of the millennium, rising from 1 in 150 in 2000.

While the increase in prevalence has slowed, it is still on the rise. There is no definitive explanation for the rise in autism diagnoses, but there are several factors that can help to explain it, including:

  • The diagnostic criteria for autism have changed significantly so that individuals with far milder symptoms are now included within the autism spectrum.
  • Awareness of autism has increased radically, with a great deal of media attention focused on autism since the late 1990s.
  • Services, support, and programs for people with autism and their families have increased, as has the acceptance of people with autism in schools, communities, and places of employment.

Autism by Ethnicity

Autism occurs in every ethnic group. In the 2018 Autism and Developmental Disabilities Monitoring (ADDM) Network report, there was no significant difference in autism diagnoses in 8-year-olds between those who were Black, White, Hispanic, and Asian/Pacific Islander.

However, some ADDM Network sites reported lower numbers of Hispanic children diagnosed with autism than White or Black children. This disparity remains to be accounted for.

Autism by Age and Gender

Autism is more prevalent in children and teens than it is in adults. About 2.21% of adults in the United States have autism compared to 2.23% of children. Because autism is a lifelong disorder and the number of children diagnosed with autism has increased radically, there will soon be many more adults with autism.

Autism is far more prevalent among boys than among girls. In fact, 3.7% of boys are diagnosed with autism, while only 0.9% of girls share the diagnosis. Autism may be underdiagnosed among girls and women.

Some states have much higher rates of autism than others. For example, only 1.7% of children in Missouri are identified as having autism, while 3.9% of children in California have an autism diagnosis. Autism is also unusually high among children in Texas, New York, and Florida.

There are state-by-state disparities among adults as well: the lowest numbers of adults with autism are in South Dakota and Arkansas, with the highest in Massachusetts and Virginia.

Causes of Autism and Risk Factors

Most cases of autism are idiopathic, meaning they are of unknown origin. Some, however, can be traced to specific factors, which include:

  • Genetics: Autism runs in families, and researchers have identified some genetic markers for autism.
  • Prenatal exposures: Exposure to specific drugs in utero, including Depakote (valproic acid), is known to be a risk factor for autism.
  • Parental age: Research suggests that older parents are more likely to have children with autism.

Vaccines and Autism

During the early part of the 2000s, now-debunked studies and media statements suggested that specific vaccines could cause autism. These studies were found to be inaccurate and even, in some cases, intentionally misleading. Vaccines do not cause autism.

 Screening and Early Detection

There is no cure for autism, but early screening and evaluation can provide access to early intervention and therapies that can lead to better outcomes.

Typically, young children are screened by their healthcare provider and recommended for more evaluation with a team that may include a pediatric neurologist, developmental pediatrician, and several therapists.

There is no medical test for autism, so testing is completed through a series of observations, interviews with parents, physical evaluations, and tests that may include:

  • Autism Diagnostic Interview-Revised (ADI-R)
  • Screening Tool for Autism in Toddlers & Young Children (STAT)
  • Social Communication Questionnaire (SCQ)
  • Modified Checklist of Autism in Toddlers (M-CHAT)

Once a child is diagnosed with autism, they become eligible for early intervention programs and may also have access to a range of preschool, summer, and/or family services. In general, children who receive intensive early intervention develop social communication skills more rapidly than those who don't.

Summary

Autism is a developmental disorder that affects how people think, speak, socialize, and behave. Autism affects people of every ethnicity, but males are more often diagnosed with it than females.

There is no medical test for autism, but early screening and evaluation can help parents access early intervention services. The number of people diagnosed with autism is on the rise.

14 Sources
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