In honor of the latest Harry Potter film (the Dementors) as well as Republican Catherine Crabill, who is simply demented (pictured, I think).
Demented (a) - insane. The adjectival form of the obsolete verb to dement meaning to drive mad. Still earlier, from the Latin dementare, (de+ment = away from mind). One no longer says, "Listening to Sarah Palin speak dements me." Although it is certainly true.