A new Centers for Disease Control and Prevention (CDC) report, considered the most complete assessment of autism to date, has found that the number of children who have an autism disorder is significantly higher than had been previously thought, and could be as high as one out of every 150 children.
Earlier estimates judged the incidence of autism disorders to be 1 in 166 children. But those estimates were based on smaller studies and used different study methods.
These findings may add further fuel to the growing debate over thimerosal, a mercury-based preservative that was used in infant vaccines up until six years ago, and is still used in flu shots.
For the new report, researchers used data from a multiyear, multistate study of 8-year-olds who were identified as having an autism spectrum disorder (ASD). ASD includes autism, PDD-NOS (pervasive developmental disorder not otherwise specified) and Asperger's disorder.
These disorders are characterized by problems with language and communication, often accompanied by repetitive or unusual behaviors, and generally begin before age 3, although they may not be diagnosed until later.