Oct. 17, 2002
M.I.N.D. INSTITUTE STUDY CONFIRMS AUTISM INCREASE
(SACRAMENTO, Calif.) — The unprecedented increase in autism in California
is real and cannot be explained away by artificial factors, such as
misclassification and criteria changes, according to the results of a large
statewide epidemiological study. "Speculation about the increase in autism in
California has led some to try to explain it away as a statistical issue or with
other factors that artificially inflated the numbers," said UC Davis pediatric
epidemiologist Robert S. Byrd, who is the principal investigator on the study.
"Instead, we found that autism is on the rise in the state and we still do not
know why. The results of this study are, without a doubt, sobering." Key
findings of the study are that: • The observed increase in autism cases cannot
be explained by a loosening in the criteria used to make the diagnosis. • Some
children reported with mental retardation and not autism did meet criteria for
autism, but this misclassification does not appear to have changed over time. •
Because more than 90 percent of the children in the survey are native born,
major migration of children into California does not contribute to the increase.
• A diagnosis of mental retardation associated with autism had declined
significantly between the two age groups. • The percentage of parent-reported
regression (loss of developmental milestones) does not differ between two age
groups. • Gastrointestinal symptoms, including constipation and vomiting,
in the first 15 months are more commonly reported by parents in the younger
group. "While this study does not identify the cause of autism, it does verify
that autism has not been over-reported in the California Regional Center System
and that some children diagnosed with mental retardation are, in fact,
autistic," Byrd said. Byrd and his research team earlier this year enrolled 684
California children who received services from one of the California Regional
Centers to participate in the study. They systematically gathered information
for children in two age groups —7 to 9 years of age and 17 to 19 years of age —
from families of 375 children with a diagnosis of full syndrome autism and 309
children with a diagnosis of mental retardation without full syndrome autism.
Byrd, a pediatrician with UC Davis Children's Hospital, and his colleagues,
conducted the study for the M.I.N.D. Institute at UC Davis to help explain
reasons behind significant increases in the number of autistic children entering
the state's 21 regional centers. A 1999 report by the California Department of
Developmental Services (DDS), which operates the centers, found a 273 percent
increase in autism cases between 1987 and 1998. The report was the catalyst for
the state Legislature and Gov. Gray Davis to direct DDS and the M.I.N.D.
Institute to identify factors responsible for the increase, funding the effort
with a $1 million appropriation. Autism is a complex and severe developmental
disorder that affects a person's ability to communicate, form relationships with
others, and respond appropriately to the environment. Those affected may avoid
making eye contact and lack the ability to read faces for signs of emotion or
other cues. Children typically do not engage in social play or games with their
peers. Unusual behaviors such as rocking, hand-flapping or even self-injurious
behavior may be present in some cases. Copies of all news releases from UC Davis
Health System are available on the Web at
http://news.ucdmc.ucdavis.edu
Editor's Note: Additional information available on these Web sites: Report to
the Legislature athttp://www.mindinstitute.org/news/report.htm
Statistics of children entering the state Regional Center system at
http://news.ucdmc.ucdavis.edu/DDS_stats.html 1999 autism report at
http://www.dds.ca.gov/Autism/pdf/Autism_Report_1999.PDF Robert Byrd's
biography athttp://news.ucdmc.ucdavis.edu/byrd_bio.html
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