ATLANTA, Dec. 18 (UPI) -- Health officials say they have no single explanation for why autism is up by half among American children.
The Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report said a study found an average of one in 110 U.S. children age 8 have an autism spectrum disorder. One-in-70 U.S. boys and 1-in-315 girls have an autism spectrum disorder -- an average 60 percent increase for boys and 48 percent for girls, officials say.
No single factor explains the changes in prevalence for the time period studied, the report said. The CDC said in a release that better detection accounts for some of the increases, but adds "a true increase in risk cannot be ruled out."
Autism spectrum disorders cause severe and pervasive impairment in thinking, feeling, language and the ability to relate to others. These disorders, usually first diagnosed in early childhood, range from a severe form called autistic disorder to pervasive development disorder to a much milder form, Asperger syndrome.
The researchers used data based on a retrospective review of health and education records from reporting communities, which includes 8 percent of the U.S. population of 8-year-olds.
"All children in the studies were 8 years old because previous research has shown that most children with an autism spectrum disorder have been identified by this age for services," the report said. "All 10 communities participating in both the earlier 2002 and 2006 study years observed an increase in identified autism spectrum disorder prevalence ranging from 27 percent to 95 percent, with an average increase of 57 percent."
