brainsick vs demented

brainsick and demented both are adjectives.

Word	Noun	Adjective	Verb	Adverb
brainsick	No	Yes	No	No
demented	No	Yes	No	No

As adjectives, brainsick and demented are synonyms defined as:

Other synonyms of brainsick include crazy, disturbed, mad, sick, unbalanced, unhinged.

brainsick (adjective)	demented (adjective)
affected with madness or insanity	affected with madness or insanity