The number of children who have
an autism disorder — as many as 1 in every 150 —
is significantly higher than previously thought, according
to a new federal report being billed as the most complete
assessment to date.
Earlier estimates placed the rate
at 1 in 166 children. But Catherine Rice, lead author
of the analysis released Thursday by the U.S. Centers
for Disease Control and Prevention, says the previous
estimates were based on smaller studies, some from other
countries, using different study methods.
Advocates for people with autism
say the results should help them push for more services.
The findings may further stoke the impassioned debate
over causes: Many blame thimerosal, a mercury-based preservative
that was used in infant vaccines up until six years ago.
Scientists concede that they don't know the cause but
say the science doesn't support a link to vaccines.
For the new CDC report, researchers
drew on information gathered in 2000 and 2002 by a multistate
surveillance network on 8-year-olds who were identified
as having an autism spectrum disorder (ASD). The category
includes autism, PDD-NOS (pervasive developmental disorder
not otherwise specified) and Asperger's disorder. All
are marked by problems with language and communication
and often are accompanied by repetitive or unusual behaviors.
ASDs begin before age 3 but may not be diagnosed until
Researchers focused on 8-year-olds
because most children with such disabilities will have
been identified by that age, Rice says.
The 2000 study, which examined children
who were born in 1992, involved sites in six states and
1,252 children with ASDs. The prevalence averaged 6.7
children out of every 1,000.
The 2002 study, which focused on
children who were born in 1994, involved 2,685 with ASDs
at sites in 14 states and found that autism prevalence
ranged from a low of 3.3 in 1,000 children in Alabama
to 10.6 in 1,000 in New Jersey. The overall average was
6.6 in 1,000 children, or about 1 in 150.
Estimates differ because ASDs vary
and some states have better diagnosis and tracking, Rice
Peter Bell, president of Cure Autism
Now, says the report is "confirmation of our worst fears,
and that is that autism is on the rise. Every two or three
years, we're given an estimate that is higher than the
CDC Director Julie Gerberding said
in a statement that it's still unknown whether there's
an actual increase in autism or just better studies. "We
do know, however, that these disorders are affecting too
many children," Gerberding said.
States facing rising autism rates
have struggled to provide services. Rice says the new
information can be used by communities to help plan for
the future needs of these children. "We know the best
outcomes come when kids are identified early," Rice says.
The revised estimates will "increase
awareness and hopefully get legislation to follow that
will give services to those with autism," says Marguerite
Colston of the Autism Society of America.