As many as one in 68 U.S. children may have autism, U.S. health officials said on Thursday, a sharp increase over an estimate of 1 in 88 children just two years ago that raises questions about why the number has risen so dramatically.
Researchers at the U.S. Centers for Disease Control and Prevention noted in their report that the data, gleaned from a study of children in 11 communities, could not be generalized to the national population.
They also did not study why the rates were so much higher, but there are some clues. In the latest report, almost half of children identified as having autism also had average or above-average IQ levels, compared with just a third of children a decade ago.
"It could be doctors are getting better at identifying these children; it could be there is a growing number of children with autism at higher intellectual ability, or it may be a combination of better recognition and increased prevalence," Coleen Boyle, director of the CDC's National Center on Birth Defects and Developmental Disabilities, said in a conference call.
Some experts believe the higher rates reflect a heightened focus on autism by parents, doctors and teachers that may be resulting in more children being diagnosed with the disorder.
In its latest report, the CDC studied medical, school and other records of 8-year-olds within 11 U.S. communities to determine whether a child had autism.
There were significantly different rates by region, ranging from 1 in 175 children in Alabama to 1 in 45 children in New Jersey, which could reflect access to healthcare and other factors.
The current study looked at fewer sites than the data reported in 2012, which included 14 communities, but the CDC said it did not change the criteria used to diagnose autism.
