31 December 2002
study finds rise in autism diagnoses
YORK (Reuters Health) - A study
conducted in Atlanta suggests that more children are being diagnosed
with autism than in the past, researchers from the Centers for Disease
Control and Prevention reported Tuesday. However, it does not shed
any more light than previous reports on whether the increase is
real or due to greater awareness or changing definitions of the
the evidence supporting claims for an "epidemic" of autism
is weak, the "subsequent controversy has put autism on the
public agenda," notes Dr. Eric Fombonne, who was not involved
in the study.
the new study, Dr. Marshalyn Yeargin-Allsopp and colleagues looked
at the prevalence of autism in 289,456 children aged 3 to 10 living
in Atlanta in 1996. They found that 34 of every 10,000 children
had symptoms of autism, a disorder characterized by social isolation,
difficulty communicating, repetitive behaviors and delayed and unusual
findings are published in the January 1 issue of the Journal of
the American Medical Association.
rate of autism found in this study was higher than the rates from
studies conducted in the United States during the 1980s and early
1990s, but it was consistent with those of more recent studies,"
the authors conclude.
four similar studies have been conducted in the US, they note. Three
done in the 1980s and early 1990s found that about 4 per 10,000
children had autism. The new results concur with those from a 1998
study conducted in Brick Township, New Jersey that found that between
40 per 10,000 children have autistic disorder and 67 per 10,000
do if all types of autism-like behavior are included.
investigators suggest a variety of factors may have contributed
to the increase in autism rates. For one, the symptoms used to diagnose
the illness have been expanded over the years and there is heightened
public awareness of the condition. This is "due in large part
to efforts of parent and advocacy groups, availability of more medical
and educational resources, increased media coverage of affected
children and families, and more training and information for physicians,
psychologists and other service providers," they write.
in 1991, the US Department of Education included autism as category
for special education services, which may have also increased diagnoses.
combined influence of these factors has probably contributed to
the identification of more individuals with autism," the authors
write. "However, it remains unclear whether specific environmental,
immunologic, genetic or unidentified factors also may have contributed
to these higher reported prevalence rates," they conclude.
other findings, the researchers found that the prevalence for autism
appeared to be similar for black and white children and about 40%
of children with autism were identified through the school system.
study is the first to get a good population-based estimate of autism
in black children, showing that the rates are similar to those found
in other youngsters, noted Fombonne in an editorial accompanying
of the McGill University and Montreal Children's Hospital in Canada,
notes that the CDC has "recently funded a surveillance network
across several states."
and other initiatives should help address more directly hypotheses
about...changes in the incidence of autism spectrum disorders,"
Journal of the American Medical Association 2003;289:49-55.