in the early stages of my father's dementia, he was part of a study (while his wife was alive) and they did an IQ test every year, and every year his IQ went down.

On a more humorous note, my DH's mother, also afflicted, went to Covina for her 50th class reunion a couple of years. Everyone in the family will laugh if you say "did she show you her pictures from Covina?" because she literally wore them out, she showed them or threatened to so many times; always like it was the VERY FIRST time.