1. Going out of one's mind: Legally, to dement is a form of mental disorder in which cognitive and intellectual functions of the brain are being prominently affected.

Impairment of memory is an early sign of dementing; total recovery is thought to be impossible since organic cerebral disease is involved.

When dementing is going on, it is also existing as "adolescent insanity" or "schizophrenia".

2. Etymology: from Latin dement, literally, "losing one's mind".