Repurposed old drugs for rejuvenation of the brain?

Has a treatment for Alzheimer's been sitting on pharmacy shelves for decades? Scientists have two possible candidates (medicalxpress.com)

Rapamycin, Metformin, Dasatinib. Repurposing already existing drugs is a smart way to bring effective treatments to the public.

And now there are indications that two old drugs, when taken as a combination, might be effective in slowing down Alzheiners and improve cognitive functions. Great news. (And cheap for the consumers).