Sharp rise in Autism without intellectual impairments

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The number of children with autism in four suburban New Jersey counties has skyrocketed since the turn of the millennium, according to a new peer-reviewed study from Rutgers University.

Researchers said the uptick was driven largely by autism going underdetected in children with average or above-average intellect. Such kids accounted for more than 70% of the cases in 2016, compared with just 57% in 2000. The retrospective study adds to a growing body of research which suggests that autism, a neurological disorder, does not necessarily overlap with intellectual disability.

“The other part of the story is that even though autism has increased in those 16 years, we expect autism to continue to increase over time,” said Josephine Shenouda, an adjunct professor of biostatistics and epidemiology at Rutgers and the study's lead author, “because we did find disparities in identification among non-Hispanic Black children and children residing in socially disadvantaged areas.”

The study examined records from 30,000 8-year-olds between 2000 and 2016 who had received a diagnosis of autism spectrum disorder. It focused on two groups: children with average or above-average IQ, and children with intellectual disabilities — the group typically monitored for autism. The study spanned four New Jersey counties — Essex, Union, Ocean and Hudson — within the New York metropolitan area.

Looking back through these records, the team found that diagnoses of autism increased fivefold in the 16-year study period for children of average or above-average intelligence. For children with intellectual disabilities, the diagnoses increased by 200% in that time.

The Rutgers study stated that disparities existed in which autistic children were also diagnosed with intellectual impairments, along racial and socioeconomic lines. White children were more likely to be identified as having autism without intellectual disability, compared to non-Hispanic Black children, who were 30% less likely to be put in the same category.

“There's a group of Black children that are basically being misidentified and not receiving services for their autism,” Shenouda said.

Autistic children in wealthy areas were also 80% more likely than children in underserved communities to be diagnosed with autism without also being diagnosed with an intellectual impairment.

Researchers said that their study sheds light on the need to better understand autism diagnoses and intellectual disability, as well as the need for consistent screening to ensure that autistic children — including those without intellectual disabilities — don’t fall through the cracks.

“The biggest problem today is that we don’t have a good screener,” Shenouda said. “The second issue is the follow-through. What happens after the child is screened? Do they receive appropriate services in referral to early intervention, for example?”

Shenouda added that misidentification for autistic children with regards to intellectual impairment was likely occurring in communities with fewer resources. “There was no real reason for children to be misidentified in different regions by [socioeconomic status],” she said. She said racial bias could possibly be a factor.