New Classification System May Explain Rise in Autism Diagnoses

Researchers said that some of the reclassification can be attributed to overlap between other neurobiological conditions and autism, as well as a broadening of the diagnostic criteria for autism. Based on his or her diagnosis, each child was assigned to one of 13 broader categories, ranging from autism to physical challenges such as blindness.

So in a new study, researchers mapped out the number of children who benefitted from special education between 2000 and 2010, and found that, while the number of special needs children remained constant over that decade, the number of children diagnosed with autism rose by a factor of five. Apparently, too many doctors misdiagnose autism, which is already a tricky condition to start with. The symptoms of autism can be diverse and generic-things like arranging objects in linear patterns or performing repetitive behaviors are considered symptoms.

It leapt to one in 150 in 2002, and reached one in 68 in 2012, reported by the US Centers for Disease Control and Prevention.

It may be that, as autism is a very unusual condition, which largely remains misunderstood, it can be easily mistaken for other disorders of the neurological or intellectual type.

He also said that the study only analyzed special education and education records so no information is there regarding high functioning or less affected individuals, not enrolled in special education. Under the legislation, students are organized into one of thirteen disability categories including autism spectrum disorder, intellectual disability, emotional disturbance, other health impairment, and specific learning disabilities.

Research bears out this concern, as I noted this week in a response to a highly problematic article by Robert F. Kennedy Jr. about autism in African-American children. “But then there is this portion of an increase that is not accounted for in a lot of statistical studies that are done”. For 9-year-olds, about 59 percent of the rise in autism is due to reassignment, and by age 15 reclassifying children can be blamed for 97 percent of the increase.

Potential reclassification from intellectual disability to autism occurred more frequently among older children compared with younger children (75% vs 48%; P =.007).

“Every patient is different and must be treated as such”, said Girirajan.

While diagnostic tools “lose specificity” when applied to people with different genetic disorders, future studies of autism prevalence should take into account detailed genetic analysis, Girirajan says.

The research was funded by the Penn State Huck Institutes of the Life Sciences and the Penn State Department of Biochemistry and Molecular Biology.