How old is your mother? Iirc PSEN1 correlates to very early AD, like late 30s early 40s. My dad had full blown AD at 65, with serious cognitive decline starting at 63, and that felt very early to us all. My dad had no AD biomarkers on full genetic scan. My heart goes out to you and your family.
Give her -- and yourself -- lithium orotate. It's an asymmetric bet: it won't hurt, but very well might help. It has been found to be effective in murine models.