The number of children diagnosed with autism or related disorders has grown
at what many call an alarming rate. In the 1970s and 1980s, about one out of
every 2,000 children had autism.
Today, the CDC estimates that one in 150 8-year-olds in the U.S. has an
autism spectrum disorder, or ASD. This expanded definition refers not only to
autism but also to a collection of brain development disorders such as
Asperger's syndrome and a condition known as pervasive developmental disorder
-- not otherwise specified (PDD-NOS). Though all the disorders share some
symptoms, they are different in other ways, including the timeline of symptoms
and the severity, according to the CDC.
Autism is a brain disorder in which communication and interaction with others are difficult. The symptoms of autism may range from total lack of communication with others to difficulty in understanding others' feelings. Because of the range of symptoms, this condition is now called autism spectrum disorder (ASD).
High-functioning autism (HFA) is at one end of the ASD spectrum. Signs and symptoms are less severe than with other forms of autism. In fact, a person with high-functioning autism usually...
The apparent rise in cases triggers two burning questions for parents,
physicians, and scientists:
Is autism truly on the rise, or do the new statistics simply reflect the
growing awareness of the condition, the expanded definition, and other
If autism is on the rise, as most experts believe, what is causing the
(Does someone you love have autism? Join other parents and caregivers on
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Autism: A True Increase or Semantics?
The jump in autism cases has spawned not only alarm but also debate about
whether the number of children with autism could have increased that much in a
relatively brief time.
"There's a lot of controversy about that," says Jeff Milunsky, MD,
director of clinical genetics and associate director of the Center for Human
Genetics at Boston University.
Two researchers who tracked the rate of autism in children born in the same
area of England from 1992 to 1995 and then from 1996 to 1998 found that the
rates were comparable, and concluded that the incidence of autism was stable.
The study was published in the American Journal of Psychiatry in
But, Milunsky says, several studies have documented an increase in the
In a recent report in the journal Archives of Disease in Childhood,
Milunsky and his colleagues point to several studies finding an increase in
autism rates. In 2003, for instance, a large study conducted in Atlanta found
that one in 166 to one in 250 children had autism, according to a report
published in the Journal of the American Medical Association.
Another study conducted by the CDC in 14 states found an overall prevalence
of one in 152, which Milunsky and others say is the generally accepted figure
Other experts say autism is on the increase but that factors other than more
children being diagnosed play a role. Some of the increase in reported cases is
because of "diagnostic substitution," says Paul Shattuck, PhD,
assistant professor of social work at Washington University in St. Louis and an
"A kid labeled autistic today could have been labeled mentally retarded
10 years ago in the same school system," Shattuck says. It wasn't until
1992 that schools began to include autism as a special education