I went to the site PubMed, and looked up Prozac -- I read the side effects for it, and memory loss was not listed as the expected side effects nor was it listed as the possible side effects. So evidently they haven't had complaints of memory loss with Prozac.
Some medications are terrible for memory loss, such as Topamax. Some people call is Dopamax. LOL I'm on that, and boy I can't remember a darn thing! I have brain damage anyway due to the fact I'm a recovering alcoholic, and i pickled my brain -- my doc said I have brain damage.
I drank heavily for 20 years -- this July I'll have 20 yrs sober, God willing.
What other meds is your wife on? Perhaps one of them is the culprit. You can look them up by clicking on "drugs" at the top of the page. Perhaps your wife needs a good physical to see what is causing her memory loss!! Might be a good idea. God bless & take care. Hugs, Lee