Mid 17th century; earliest use found in Henry Parker (1604–1652), political writer. Originally from dementate + -ed; in later use perhaps an alteration of demented.
Definition of dementated in US English:
dementated
adjectivedɪˈmɛnteɪtɪd
Demented.
Origin
Mid 17th century; earliest use found in Henry Parker (1604–1652), political writer. Originally from dementate + -ed; in later use perhaps an alteration of demented.