Rising autism diagnoses stem from expanded criteria, better detection, and older parents.

Evidence

Despite billions spent on autism research, we do not know why some brains are wired differently. We do have some answers, however, to the question of why there has been a dramatic increase in diagnosed cases of autism over the last two to three decades, to the point that the Autism and Developmental Disabilities Monitoring Network, a program funded by the U.S. Centers for Disease Control, reports that 1 in every 44 eight-year-olds was diagnosed with autism in 2018, up from 1 in 150 in 2000. One answer is that the clinical definition of autism expanded significantly in the 1990s to include many neuroatypical people who would have previously been excluded. This, in turn, led to many more people deciding to get tested, which contributed to a spike in diagnoses and greater understanding of the different ways autism presents. More recently, doctors have gotten better at recognizing autism in girls, who tend to mask it better, and, to a lesser extent, in Black, Indigenous, and Latino boys, who still are too likely to be disciplined and/or written off as “troublemakers,” rather than be supported and accommodated for their neurodiversity. There may also be another important factor in the rising numbers. Parents like me are having kids later. Multiple peer-reviewed studies show that children born to older parents are more likely to be diagnosed with autism. — Naomi Klein, Doppelganger, 658

Categorization

• DEFINE: Crisply separates the unexplained cause (why brains differ) from the well-understood reasons for rising diagnosis counts — a distinction anti-vax discourse deliberately collapses.