CDC Releases New Data On Autism Spectrum Disorders (ASDs) From Multiple Communities In The United States

The Centers for Disease
Control and Prevention (CDC) reported findings today from the first and
largest summary of prevalence data from multiple U.S. communities
participating in an autism spectrum disorder (ASD) surveillance project.
The results showed an average of 6.7 children out of 1,000 had an ASD in
the six communities assessed in 2000, and an average of 6.6 children out of
1,000 having an ASD in the 14 communities included in the 2002 study. All
children in the studies were eight years old because previous research has
shown that most children with an ASD have been identified by this age for
services.


For decades, the best estimate for the prevalence of autism was four to
five per 10,000 children. More recent studies from multiple countries using
current diagnostic criteria conducted with different methods have indicated
that there is a range of ASD prevalence between 1 in 500 children and 1 in
166 children. The CDC studies provide information on the occurrence of ASDs
in fourteen communities in the United States.



"Our estimates are becoming better and more consistent, though we can't
yet tell if there is a true increase in ASDs or if the changes are the
result of our better studies," said CDC Director Dr. Julie Gerberding. "We
do know, however, that these disorders are affecting too many children."



Overall, the 2000 study found ASD rates ranged from one in 222 children
to one in 101 eight-year old children in the six communities studied. The
2002 study found ASD rates ranging from one in 303 to one in 94 among
eight-year old children. The average finding of 6.6 and 6.7 per 1,000
eight-year-olds translates to approximately one in 150 children in these
communities. This is consistent with the upper end of prevalence estimates
from previously published studies, with some of the communities having an
estimate higher than those previously reported in U.S. studies.



ASDs are developmental disabilities and are defined by considerable
impairments in social interaction and communication and the presence of
unusual behaviors and interests. They can be diagnosed as early as 18
months and last throughout a person's life. ASDs include autistic disorder,
pervasive developmental disorder - not otherwise specified (PDD-NOS,
including atypical autism), and Asperger syndrome.



The 2000 study included approximately 4.5 percent of U.S.
eight-year-old children born in 1992 from six states -- Arizona, Georgia,
Maryland, New Jersey, South Carolina and West Virginia. A total of 1,252
eight-year olds were identified as having an ASD.



The 2002 study included approximately 10 percent of U.S. eight-year-old
children born in 1994 from 14 states -- Alabama, Arizona, Arkansas,
Colorado, Georgia, Maryland, Missouri, New Jersey, North Carolina,
Pennsylvania, South Carolina, Utah, West Virginia and Wisconsin. A total of
2,685 eight-year-olds were identified as having an ASD.
















"It is extremely difficult to accurately estimate the number of
children who have an ASD," said Dr. Marshalyn Yeargin-Allsopp, chief of
CDC's autism program. "Medical records often do not provide such
information, and identification is often made by schools or education
specialists. The data reported today by the Autism and Development
Disabilities Monitoring (ADDM) Network was designed to provide more
consistent and reliable estimates."



"It's important to note that these studies don't provide a national
estimate, but that they do confirm that ASDs in the areas surveyed are more
common in these communities studied than previously thought," said Yeargin-
Allsopp. "We need to continue efforts to monitor the prevalence of ASDs and
to improve our understanding of these disorders. Good estimates of how many
children in a community may have an ASD will also help school and health
officials in their planning and intervention efforts."



The purpose of CDC's ADDM project was to develop a system for better
understanding the size and characteristics of the population of children
with an ASD.



In addition to trying to measure the number of children with an ASD,
the studies also looked at when parents and others first noted signs of
developmental concerns in their children. The 2000 and 2002 studies found
51 percent to 88 percent of children with ASDs had documented developmental
concerns before the age of three. Half of the children were diagnosed with
an ASD when they were between four and one half and five and one half years
old. The most commonly documented concerns were in language development,
followed by social development.



"We don't know the causes of ASDs, but we do know that if we can
identify autism and other developmental problems in children early, they
can begin receiving appropriate interventions sooner," said
Yeargin-Allsopp. "It is important for parents, health care professionals
and childcare providers to recognize developmental milestones such as
smiling, pointing and waving bye- bye. It's also important that health care
professionals give children routine developmental and autism-specific
screenings."



While these studies did not investigate the causes of ASDs, CDC's
Centers for Autism and Development Disabilities Research and Epidemiology
(CADDRE) Network is doing a multi-state study to help identify factors that
may put children at risk for ASDs and other developmental disabilities.



This project is being conducted by CDC, University of Alabama at
Birmingham, University of Arizona at Tucson, University of Arkansas,
Colorado Department of Public Health and Environment, Johns Hopkins
University, Washington University in St. Louis, University of North
Carolina at Chapel Hill, University of Medicine and Dentistry of New Jersey
in Newark, University of Pennsylvania School of Nursing, Medical University
of South Carolina, University of Utah, Marshall University and the
University of Wisconsin- Madison. Six sites participated in the 2000
project, and an additional eight were added for the 2002 project.



CDC also has a public awareness campaign titled, "Learn the Signs. Act
Early" designed to increase the awareness of child development by educating
parents, health care professionals and childcare providers on the
importance of tracking a child's social and emotional development,
including the potential early warning signs of autism and other
developmental disabilities. To learn more about "Learn the Signs. Act
Early," visit cdc/actearly.



For more information on CDC's work on autism, please visit
cdc/autism.


Centers for Disease Control and Prevention

cdc/autism