1925. In Alberta, Canada, the "Lunatics' Estates Act" of 1916 is renamed the "Estates of the Mentally Incompetent Act".
Section 3(b) of this Act states:
MENTALLY INCOMPETENT' includes every person who is mentally diseased, an idiot, of unsound mind or feeble-minded."
You can view the Act here.
-Amy Dyrbye
Province of Alberta. (1925). An Act to amend the Lunatics' Estates Act. Retrieved from http://www.ourfutureourpast.ca/law/page.aspx?id=2904563.