With denial, there is a short conscious recognition of a problem, which is then relegated to the unconscious where it won't bother us - we hope. There's something wrong here, and I am not going to deal with it-until there are some kind of symptoms, and a good therapist or spouse can dig it out of my unconscious, lay it on the table, and cure my neurotic complex. A defense mechanism.
With dementia, the same brain that is losing analyzing functioning, is also losing the ability to "analyze itself, " like the Zen koan how can your eye see itself? or point to your right hand index finger with your right hand index finger.
In short, the dementia brain doesn't even know there is anything to defend against, put into the unconscious, or deny.
What's the problem with putting the container of milk in the dishwasher? I didn't do that. Ya wanna fight about it?
It's so sad.