addle
He showed no signs of the addled thinking that comes with dementia.
His brain is so addled that he doesn't know what day it is.
We loved her for her addled eccentricities.

SMART Vocabulary: related words and phrases

Confusion, confusing and feeling confused
all of a doodahidiom
all over the placeidiom
alphabet soup
at seaidiom
at sixes and sevensidiom
discombobulation
disordered
disorganization
disorganized
disorientating
muddle something up
muddle-headed
muddled
mush
muzzily
unaccountable
unaccountably
unexplainable
unexplained
unsearchable