Dementio, dementis, dementîre. Lucr. To be mad: to dote: to be foolish.
Lewis and Short: Latin dictionary
dēmentĭo, īre, 4, v. n. [id.], to be out of one's senses, to be mad, to rave (anteand post-class.): dementit deliraque fatur, Lucr. 3, 464: sese mea magia in amorem inductam dementire, App. Mag. p. 324, 9: aliquis instinctu daemonis percitus dementit, effertur, insanit, Lact. 4, 27 med.