A new report came out today: Changes in Prevalence of Parent-reported Autism Spectrum Disorder in School-aged U.S. Children: 2007 to 2011–2012. I’ll come back for more detail and discussion soon, but the bottom line: the autism prevalence estimate for the US is now about 2%. 3.23% for boys.
Here is the press release for this:
CDC and HRSA issue report on changes in prevalence of parent-reported
Autism Spectrum Disorder in school-aged children
Who: CDC’s National Center for Health Statistics and the Health Resources and Services Administration
What: “Changes in Prevalence of Parent-Reported Autism Spectrum Disorder in School-Aged Children: 2007 to 2011-2012.”
The report was co-authored by HRSA and data collection was conducted by the CDC. The data come from the National Survey of Children’s Health, a nationally representative phone survey of households with children. This survey is conducted every four years.
Main findings of the report:
· The prevalence of parent-reported ASD among children aged 6-17 years was 2 percent in 2011-2012 compared to 1.2 percent in 2007.
· The change in prevalence estimates was greatest for boys and for adolescents aged 14 to 17 years.
· Children who were first diagnosed in or after 2008 were more likely to have milder ASD than those diagnosed in or before 2007.
· Much of the increase in the prevalence estimates from 2007 to 2011-2012 for school-aged children was the result of diagnoses of children with previously unrecognized ASD.
The report is available at http://www.cdc.gov/nchs.
For information about HRSA’s autism efforts visit http://mchb.hrsa.gov/programs/autism/index.html.
For information about CDC’s autism efforts visit http://www.cdc.gov/ncbddd/autism/index.html.
As indicated above, there are clearly social factors at play involving identification of individuals previously unidentified. For example: If one looks at the prevalence estimate for 6-9 year olds in 2007, a value of 1.31% was obtained. In 2010-11, the prevalence for children born in the same years (now aged 10-13 years old) is 2.39%. In other words, children born in the years 1998-2001 saw an big increase in the estimated autism prevalence.
For the 2010-11 report, about 1/3 of the children were diagnosed after 2008. These are children 6-17 years old, so they were born in 2005 and before. About 30% of children born in 1998-2001 were diagnosed after 2008. These are children aged 7-13.
And, yes, this means that the thimerosal hypothesis, the notion that the increased exposure to thimerosal from vaccines in the 1990’s cause an autism-epidemic, is even less viable. There are obviously a number of social influences behind the increase in autism prevalence estimates in the U.S.. These could mask a “real” increase (or, interestingly, a real decrease). But had thimerosal been a primary driver of the increased prevalence, the prevalence would be dropping. The prevalence for children 6-9 years old, children born after the phase out of thimerosal, now is estimated at 1.82%.
By Matt Carey