dementation
/ˌdiːmɛnˈteɪʃn/noun
The action of making a person demented; the fact or condition of being demented; madness.
Origin
Late 16th century; earliest use found in Richard Robinson (fl. 1573–1589), poet. From post-classical Latin dementation-, dementatio insanity from dementat-, past participial stem of dementare + classical Latin -iō.