Autism More Widespread Than Previously Estimated
One in 150 children in the U.S. has an autism spectrum disorder, a higher rate than previously estimated, according to a CDC study published on Friday in the agency's Morbidity and Mortality Weekly Report, the Washington Post reports (Weiss, Washington Post, 2/9).
The study -- the most comprehensive to date on autism -- collected data from 2000 and 2002 about eight-year-olds, the age by which most autism-related disabilities have been identified. The 2000 data included children born in 1992 in six states and found 1,252 children with ASDs, for a prevalence of 6.7 children out of every 1,000.
The 2002 data included children born in 1994 in 14 states and found 2,685 children with ASDs, for a prevalence of 6.6 in 1,000 (Manning, USA Today, 2/9).
If extrapolated nationally, 560,000 U.S. children under the age of 21 would be affected by an ASD.
To identify autism-related disabilities, researchers looked at descriptive reports by teachers -- not medical exams -- which were reviewed by experts for words describing common ASDs (Washington Post, 2/9).
Prevalence rates varied by state: Alabama had the lowest rate of one in 300, while New Jersey had the highest rate at one in 100. CDC officials attribute these differences in rates to lack of access to some of Alabama's school records, leading to a low estimate, and to New Jersey's higher level of awareness about ASDs and greater availability of services for affected children (Carey, New York Times, 2/9).
The study also showed that most children were not diagnosed until age four or five, which is "later than health experts would like it see," according to the Wall Street Journal. Signs of autism usually are present before age three (Corbett Dooren, Wall Street Journal, 2/9).
The results of the study show an increase in the estimated prevalence of autism from previous figures that put the rate between one in 166 to one in 175 (Reuters/Washington Times, 2/9). Estimates in the 1980s put the rate at higher than one in 200 (New York Times, 2/9).
Researchers note that the study results likely do not indicate a rise in actual autism rates because study methodology and population sizes were different between the CDC research and previous studies.
Catherine Rice, a CDC scientist and the study's lead author, said it is difficult to determine whether more children have autism than in the past or whether there has been a change in the way they are diagnosed, the Journal reports.
CDC will continue collecting data from 2004 and 2006 using similar methodology (Wall Street Journal, 2/9).
Rice cautioned against extrapolating the results of the study nationwide because the states surveyed are not demographically representative of the entire country, but she added that the results showed impressive consistency from state to state (Emery, Baltimore Sun, 2/9).
CDC officials said that states can use the estimates to budget their special education and mental health services resources (Washington Post, 2/9).
ASDs encompass a range of impairments in social skills and communication, along with unusual behavior or interests, and include autism, Asperger's syndrome and pervasive developmental disorders (Wall Street Journal, 2/9). Researchers do not know the cause of autism, but it is believed to be caused by a combination of genetic and environmental factors.
Some groups attribute autism to the use of mercury-containing preservatives in vaccines, but those claims have never been scientifically proven, according to the Institute of Medicine (Reichard, CQ HealthBeat, 2/8).
The results show that autism is an "urgent public health issue" and a "major public health concern," according to Marshalyn Yeargin-Allsopp, chief of the developmental disability branch of CDC (Washington Post, 2/9).
CDC Director Julie Gerbering said, "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" (Mason, Contra Costa Times, 2/9).
Rice said, "There's been a lot of concern about what the prevalence of autism is in the United States, and we haven't really had the data systems to answer that completely." She added, "We really do think that these data are important because they represent the most complete and accurate picture of autism spectrum disorders in the United States to date" (Reuters/Washington Times, 2/9).
Craig Newschaffer, an autism expert at the Drexel University School of Public Health who helped formulate some of the study's results, said, "This study gives us the first real high quality data that confirm that autism is more common than we wish it was and an important public health problem" (Goldstein, Philadelphia Inquirer, 2/9).
Marguerite Colston of the Autism Society of America said that the study's estimates will "increase awareness and hopefully get legislation to follow that will give services to those with autism" (USA Today, 2/9).
Lee Grossman, CEO of ASA, said, "Finally, we can end the debate on the prevalence of autism in our nation and focus on getting the services and supports the families need" (Reuters/Washington Times, 2/9).
The study is available online. Note: You will need Adobe Acrobat Reader to view the study.
Several broadcast programs reported on the study:
- ABC's "Good Morning America": The segment includes comments from Grossman and a parent of a child with autism (McKenzie, "Good Morning America," ABC, 2/9). Video of the segment is available online.
- CBS' "Evening News": The segment includes comments from Yeargin-Allsopp; Gary Goldstein, clinical scientist adviser for Autism Speaks; and a parent of a child with autism (LaPook, "Evening News," CBS, 2/8). Video of the segment and expanded CBS coverage are available online.
- NBC's "Nightly News": The segment includes comments from Yeargin-Allsopp, Goldstein and the parents of autistic triplets (Gaston, "Nightly News," NBC, 2/8). Video of the segment is available online.