The difference between Alzheimer's and cancer

When I knew he had Alzheimer's, I wanted to fill his days with memory-makers, just as I would if he had been diagnosed with some type of incurable cancer. The problem is, no matter how unforgettable a day or an hour might be, he's going to forget it. It's the nature of the beast eating his brain. So I slog on, knowing these good days and hours are disappearing behind him, and I'm left to remember alone.