i Register
In some senses, dement is marked as archaic. Watch for register when choosing this word.
adj
Demented.
verb
To make (someone) demented; to drive mad].
To show signs of dementia; to develop dementia.
noun
Someone afflicted with dementia.
The patients are more or less chronic dements, sufficiently harmless and trustworthy to be employed in farm labour and sufficiently intelligent to be of use.