My mom was on it for the last two years and over that time her memory got worse, she had confusion and fears at odd times, and worst she had awful recurring nightmares and sleep terrors and other sleep disturbances. We even tried her on anti-psychotics for a time. A total mistake which threatened to turn her into a zombie that slept the day away.
I had a moment of clarity and took her off the Aricept 3 weeks ago. It's like I got my mom back! Sure, she still has awful short-term memory, and she repeats stuff, but her sense of humour, her ability to hold a conversation, and her personality has returned. She can watch a TV show again and follow it, and hasn't had ONE nightmare or sleep disturbance. This, despite the fact that she had to have a tooth pulled and was in great pain (usually sickness makes dementia sufferers more confused, but Mom's been fine!)
I accept that she has age-related dementia and we don't know where it will go, or how it will end, but I will never put her on memory meds again.