@serge @Garwboy

although the word "autism" wasn't used, it appears that the dis order was known in , at least, the early 1800s.
beyondthespectrummovie.com/a-h

see also here, autism in the mid 1800s

smithsonianmag.com/science-nat

and this notes how part of the increase in diagnosis is due to closure of "mental hospitals"
ncbi.nlm.nih.gov/pmc/articles/