Autism incidence vs autism diagnosis

RFK Jr has dishonestly portrayed the increase in autism diagnoses over the past 20 years as an increase in incidence of autism to justify his claim of an environmental cause for autism. Multiple published and refereed reports using twin pair studies show 60-90% heritability for autism, and those are probably underestimates. What changed in the last 20 years is the diagnostic criteria for autism and the systematic application of the new diagnostic criteria.

A friend of mine has an autistic son who is in his 30s. Just to underscore the impact of how diagnostic criteria have change, here’s my friend’s experience with his son:

“By age [of diagnosis], T__ would fall into the late group (age 19),  but he was actually early in the sense that he could have been diagnosed much sooner (age 2) if physicians were more aware of autism. In the 90s it was all about ADHD and everyone seemed stumped when they couldn't make him fit that diagnosis. I remember a psychiatrist who watched T__ play for less than 5 minutes and then described everything about him; difficulty transitioning to new activities, parallel play, sensitive to clothing labels, sensitive to loud noises, emotional meltdowns, wears the same clothes, etc., etc.  She basically recited a list of seemingly unrelated traits that were classic ASD and fit T__ perfectly. I was astounded. I thought she was magic.  But she never said autism.  We could have known when he was 2. Autism just wasn't diagnosed very much at the time (although she must have known). There was also a psychologist who spent months showing T__ drawings of facial expressions, trying to teach him nonverbal cues. Same thing.  Duh.”

Society is better off with the current diagnostic criteria. Understanding autism means we can intervene early to maximize the potential of every citizen. Lying about autism, like RFK Jr does, harms Americans and America.