A bit of the history of UK mental healthcare and the word idiot

http://www.institutions.org.uk/poor_law_unions/imbeciles.htm

"
1913
The Mental Deficiency Act 1913
Four "classes" of Mental Deficiency were defined:

Idiot ~ unable to protect themselves from common dangers.

Imbecile ~ could protect themselves from common dangers, but unable to
take care of themselves.

Feeble-Minded ~ required care to protect themselves.

Moral Defectives ~ criminal or vicious personalities. Unmarried Mothers
also became absorbed into this category!

The Board of Control was established who took on the powers and
responsibilities of the Lunacy Commissioners.
"

The word itself has been around for much longer.
http://www.etymonline.com/index.php?term=idiot