There are several meds prescribed to slow the progression of AD. I can't speak for all of them, but I do know that my mom has been on Aricept for 2 years and also takes several other meds as well....one for high blood pressure, one of osteoporosis, drops for glaucoma and Paxil for anxiety.
The DR. that 1st prescribed the Aricept never mentioned coming off any of the meds. Her 2nd neurologist has prescribed some of these meds she is currently on knowing she was already on the Aricept.
I am not sure which AD med your grandmother's DR. was referring to, but perhaps you could ask him about the Aricept. It has really helped my mom. She is still in decine, but it has been a VERY slow process.
Good luck to you.
SciTeach