My mom has post stroke dementia effecting her short term memory. Neuro wants to put her on Aricept and Namenda. Any advice?

Funny though, her short term memory can be selective. What I mean is if it is something extremely important like going to visit someone or a special up coming event, she remembers every day and brings it up. Yet when it comes to conversations and Q and A sessions, what did you do last night, what was for lunch....etc. .... my mom has zero recall.