Etymologically, autist is pretty much the same as idiot. Curious, isn't it?
Online Etymology Dictionary wrote:
autistic (adj.)
1912 (Bleuler), from autism (q.v.). Noun meaning "person with autism" is recorded from 1968 (earlier in this sense was autist).
autism (n.)
1912, from German Autismus, coined 1912 by Swiss psychiatrist Paul Bleuler (1857-1939) from comb. form of Greek autos- "self" (see auto-) + -ismos suffix of action or of state. The notion is of "morbid self-absorption."
idiot (n.)
early 14c., "person so mentally deficient as to be incapable of ordinary reasoning;" also in Middle English "simple man, uneducated person, layman" (late 14c.), from Old French idiote "uneducated or ignorant person" (12c.), from Latin idiota "ordinary person, layman; outsider," in Late Latin "uneducated or ignorant person," from Greek idiotes "layman, person lacking professional skill" (opposed to writer, soldier, skilled workman), literally "private person (as opposed to one taking part in public affairs)," used patronizingly for "ignorant person," from idios "one's own" (see idiom).