A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Winter, 2023 | Number 1, Volume 37

New Jersey Autism Study shows large increase in cases of autism without intellectual disability

A  new study reports that diagnosed cases of autism spectrum disorder (ASD) in the New York–New Jersey metro region rose sharply between 2000 and 2016. Additionally, it found that the largest increase occurred among children without intellectual disabilities. 

“One of the assumptions about ASD is that it occurs alongside intellectual disabilities,” says lead author Josephine Shenouda. “This claim was supported by older studies suggesting that up to 75 percent of children with autism also have intellectual disability.” However, she says, “What our paper shows is that this assumption is not true. In fact, in this study, two in three children with autism had no intellectual disability whatsoever.”

 The researchers used biannual data from the ongoing New Jersey Autism Study to identify 4,661 eight-year-olds with ASD in four New Jersey counties during the study period. Of these, only about 32 percent had an intellectual disability. Further analysis showed that rates of ASD co-occurring with intellectual disability increased two-fold between 2000 and 2016, while rates of ASD with no intellectual disability increased five-fold. 

Senior study coauthor Walter Zahorodny comments, “Better awareness of and testing for ASD does play a role. But the fact that we saw a 500 percent increase in autism among kids without any intellectual disabilities—children we know are falling through the cracks—suggests that something else is also driving the surge.” 

The Rutgers study found that black children with ASD and no intellectual disabilities were 30 percent less likely to be identified compared with white children, and that children in wealthy areas were 80 percent more likely to be identified than children in poorer areas. 

Shenouda says, “With up to 72 percent of the ASD population having borderline or average intellectual ability, emphasis should be placed on early screening, early identification and early intervention. Because gains in intellectual functioning are proportionate with intense intervention at younger ages, it’s essential that universal screening is in place, especially in underserved communities.” 

Shenouda and colleagues say their findings challenge the assumption that autism generally occurs alongside intellectual disability

Citations

“Prevalence and disparities in the detection of autism without intellectual disability,” Josephine Shenouda, Emily Barrett, Amy L. Davidow, Kate Sidwell, Cara Lescott, William Halperin, Vincent M. B. Silenzio, and Walter Zahorodny, Pediatrics, November 2023 (free online). Address: Josephine Shenouda, Department of Pediatrics, Rutgers New Jersey Medical School, 185 South Orange Ave F-511, Newark, New Jersey 07103, [email protected]

—and— 

“Study logs five-fold increase in autism in New York-New Jersey region,” news release, Rutgers University-New Brunswick, January 18, 2023