Does a person with dementia know that they have a problem?

My Dad was told, and made an announcement to one of his service clubs. We didn't find out until years later. They were respectful to him, and gave him lots of grace. We didn't know anything other than Dad's quirkiness was increasing. It didn't make sense, and sort of kept us away. Then his familiar bursts of anger turned to catastrophic episodes. He started shadowing Mom. Other strange behaviors appeared and became increasingly bizarre; then dangerous, and he had to move from home to safety.

Now, only 17 months later, he smiles when he sees me, and calls his daughter, "sister." When I left tonight, he called Mom's name out in distress and desperation, and I had to go back and get the nurse to distract him so I could go home for supper. Don't know what he knows, but sometimes it rips my heart to shreds.