What Is Autism?

Autism is a complex developmental disability that typically appears during the first two years of life and is the result of a neurological disorder that affects the functioning of the brain, impacting development in the areas of social interaction and communication skills. Both children and adults on the autism spectrum typically show difficulties in verbal and non-verbal communication, social interactions, and leisure or play activities.


Autism is one of five disorders that fall under the umbrella of Pervasive Developmental Disorders (PDD), a category of neurological disorders characterized by “severe and pervasive impairment in several areas of development.”

Prevalence

Autism is the most common of the Pervasive Developmental Disorders, affecting an estimated 1 in 100 births (Centers for Disease Control Prevention, 2007). Roughly translated, this means as many as 1.5 million Americans today are believed to have some form of autism. And this number is on the rise.

Based on statistics from the U.S. Department of Education and other governmental agencies, autism is growing at a startling rate of 10-17 percent per year. At this rate, the Autism Society estimates that the prevalence of autism could reach 4 million Americans in the next decade.

Autism knows no racial, ethnic, or social boundaries; family income levels; lifestyle choices; or educational levels, and can affect any family and any child.

And although the overall incidence of autism is consistent around the globe, it is four times more prevalent in boys than in girls.
Source: Autism Society of America Web Page



Facts and Stats

• 1 percent of the population of children in the U.S. ages 3-17 have an autism spectrum disorder.1

• Prevalence is estimated at 1 in 110 births.2

• 1 to 1.5 million Americans live with an autism spectrum disorder.3

• Fastest-growing developmental disability; 1,148% growth rate.4

• 10 - 17 % annual growth.5

• $60 billion annual cost.6

• 60% of costs are in adult services.7

• Cost of lifelong care can be reduced by 2/3 with early diagnosis and intervention.8

• In 10 years, the annual cost will be $200-400 billion.9

• 1 percent of the adult population of the United Kingdom have an autism spectrum disorder.10

• The cost of autism over the lifespan is 3.2 million dollars per person.11

2003, 2006 Copyright the Autism Society. All rights reserved.

1. Pediatrics, October 5, 2009, based on a National Children’s Health Survey done with 78,000 parents in 2007.

2. "Prevalence of Autism Spectrum Disorders - Autism and Developmental Disabilities Monitoring Network, United States, 2006." Department of Health and Human Services, Centers for Disease Control and Prevention. Morbitity and Mortality Weekly Report, 18 December 2009.

3. Based on the autism prevalence rate of 1 in 150 (Centers for Disease Control and Prevention, 2007) and 2000 U.S. Census figure of 280 million Americans.

4. “Autistic Spectrum Disorders: Changes in the California Caseload, An Update June 1987 June 20007.” Cavagnaro, Andre T., California Health and Human Services Agency. State of California 2003 survey of developmental disabilities.

5. Autism Society estimate based on 2003 US state educational data.

6. Autism Society estimates based on UK study by Jarbrink K, Knapp M, 2001, London School of Economics: "The economic impact on autism in Britain," 5 (1): 7-22.

7. Autism Society estimate.

8. Autism Society estimate, using Government Accounting Office Report on Autism 2007.

9. Autism Society estimate.

10. Autism Spectrum Disorders in adults living in households throughout England," Report from the Adult Psychiatric Morbidity Survey 2007, a survey carried out for the United Kingdom NHS Information Centre for health and social care.

11. Arch Pediatric Adolesc Med. 2007;161:343-349.


There is no known single cause for autism, but it is generally accepted that it is caused by abnormalities in brain structure or function. Brain scans show differences in the shape and structure of the brain in children with autism versus neuro-typical children. Researchers are investigating a number of theories, including the link between heredity, genetics and medical problems. In many families, there appears to be a pattern of autism or related disabilities, further supporting a genetic basis to the disorder. While no one gene has been identified as causing autism, researchers are searching for irregular segments of genetic code that children with autism may have inherited. It also appears that some children are born with a susceptibility to autism, but researchers have not yet identified a single "trigger" that causes autism to develop.

Other researchers are investigating the possibility that under certain conditions, a cluster of unstable genes may interfere with brain development, resulting in autism. Still other researchers are investigating problems during pregnancy or delivery as well as environmental factors, such as viral infections, metabolic imbalances, and exposure to environmental chemicals.

Genetic Vulnerability

Autism tends to occur more frequently than expected among individuals who have certain medical conditions, including Fragile X syndrome, tuberous sclerosis, congenital rubella syndrome, and untreated phenylketonuria (PKU). Some harmful substances ingested during pregnancy also have been associated with an increased risk of autism. Read more about related conditions.

Environmental Factors

Research indicates that other factors besides the genetic component are contributing to the rise in increasing occurrences of ASD, such as environmental toxins (e.g., heavy metals such as mercury), which are more prevalent in our current environment than in the past. Those with ASD (or those who are at risk) may be especially vulnerable, as their ability to metabolize and detoxify these exposures can be compromised. Read more about environmental health and autism.

(Last updated: 25 January 2008)

There are no medical tests for diagnosing autism. An accurate diagnosis must be based on observation of the individual's communication, behavior and developmental levels. However, because many of the behaviors associated with autism are shared by other disorders, various medical tests may be ordered to rule out or identify other possible causes of the symptoms being exhibited. At first glance, some persons with autism may appear to have mental retardation, a behavior disorder, problems with hearing, or even odd and eccentric behavior. To complicate matters further, these conditions can co-occur with autism. However, it is important to distinguish autism from other conditions, since an accurate diagnosis and early identification can provide the basis for building an appropriate and effective educational and treatment program.

A brief observation in a single setting cannot present a true picture of an individual's abilities and behaviors. Parental (and other caregivers' and/or teachers’) input and developmental history are important components of making an accurate diagnosis.