Autism Information Center
Autism Spectrum Disorders Overview
Autism is one of a
group of disorders known as autism spectrum
disorders (ASDs). ASDs are
developmental disabilities that cause substantial impairments in
social interaction and communication and the presence of unusual
behaviors and interests. Many people with ASDs also have unusual
ways of learning, paying attention, and reacting to different
sensations. The thinking and learning abilities of people with ASDs
can vary—from gifted to severely challenged. An ASD begins before
the age of 3 and lasts throughout a person's life.
pervasive developmental disorder - not otherwise specified (PDD-NOS,
including atypical autism), and
Asperger syndrome. These conditions all have some of the
same symptoms, but they differ in terms of when the symptoms start,
how severe they are, and the exact nature of the symptoms. The three
conditions, along with
Rett syndrome and
childhood disintegrative disorder, make up the broad
diagnosis category of pervasive developmental disorders.
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ASDs occur in all racial, ethnic, and socioeconomic groups and are
four times more likely to occur in boys than in girls. CDC’s Autism
and Developmental Disabilities Monitoring
(ADDM) Network released data in 2007 that found about 1 in 150
8-year-old children in multiple areas of the United States had an
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can autism spectrum disorders be detected?
ASDs can often be
detected as early as 18 months. While all children should be watched
to make sure they are reaching developmental milestones on time,
children in high-risk groups—such as children who have a parent or
brother or sister with an ASD—should be watched extra closely. A
child with any of the
warning signs of ASDs
should be checked by a health care professional.
that early intervention can greatly improve a child’s development., CDC is working
with national partners on a public awareness campaign to educate parents about how important
it is to track their child’s development in the first few years of
life. The campaign, “Learn
the Signs. Act Early,” teaches parents, health care
professionals, and child care providers about early childhood development,
including early warning signs of autism and other developmental
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Is autism a new disorder?
Autism may seem
like a modern disorder, but it’s not. People have probably lived
with what we know today as autism spectrum disorders throughout
history. Some of the earliest published descriptions of behavior
that sounds like autism date back to the 18th century. But the
disorder did not have a name until the middle of the 20th
was first identified as a specific disorder in 1943 by child
psychiatrist Dr. Leo Kanner. Based on a study of 11 children, Dr.
Kanner published the first description of what he called “autistic
disturbances of affective contact.”
At about the same time, German scientist Dr. Hans Asperger, based on
his study of 400 children, described another form of autism that
became known as Asperger syndrome.
The criteria used
to diagnose ASDs have changed many times since Kanner’s original
here to see those changes.
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We have learned a
lot about the symptoms of ASDs and have improved efforts to track
the disorders, but we still don’t know a lot about the causes of
ASDs. Scientists think that both genes and the environment play a
role, and there might be many causes that lead to ASDs.
Family studies have been most helpful in understanding how genes
contribute to autism. Studies have shown that among identical twins,
if one child has autism, then the other will be affected about 75%
of the time. In non-identical twins, if one child has autism, then
the other has it about 3% of the time. Also, parents who have a
child with an ASD have a 2%–8% chance of having a second child who
is also affected.,
For most people
with ASDs, the cause is not known. But ASDs tend to occur more often
than expected among people who have certain other medical
Fragile X syndrome,
congenital rubella syndrome, and untreated
phenylketonuria (PKU). Some harmful drugs taken during pregnancy also have been linked with
a higher risk of autism, specifically, the prescription drug
CDC’s Centers for Autism and Developmental Disabilities Surveillance
and Epidemiology (CADDRE) are working together on a large,
population-based study to better understand the possible risk
factors for and causes of autism. Called the Study to Explore Early
Development (SEED), this project will help answer the many questions
needed to find the causes of autism and—if possible—come up with
strategies to prevent this complex disorder.
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Disclaimer: We have provided a link to
these sites because they have information that may be of interest to you. CDC does not necessarily endorse the views or information presented on
these sites. Furthermore, CDC does not endorse any commercial products or information that may be presented or advertised on these sites.
Handleman, J.S., Harris, S., eds. Preschool Education
Programs for Children with Autism (2nd ed).
Austin, TX: Pro-Ed. 2000.
 National Research Council. Educating
Children with Autism. Washington, DC: National Academy
 Kanner, L. Autistic disturbances of
affective contact. Nervous Child 1943; 2:217-250.
 Asperger, H. Die “Autistichen
Psychopathen” Kindesalter. Arch Psychiatr Nervenkr 1944;
C, Van Naarden Braun K, Yeargin-Allsopp M. The
Prevalence and the Genetic Epidemiology of Developmental
Disabilities. In: Genetics of Developmental
Disabilities. Merlin Butler and John Meany eds. 2004
(Table 3, p. 716-717).
R, Trentacoste V, Rapin I. The Genetics of Autism.
February 09, 2007
Content source: National Center on Birth Defects and Developmental