I've blogged about the possible link between Tamoxifen and memory/dementia:
here and here.
This is a link to an interesting article on this topic:
Another interesting article - see the abstract at the start:
Perhaps most interestingly, Tamoxifen appears to be a drug that researchers turn to when they wish, for whatever reason, to impair the memory of mice: as this link shows - and it's an interesting article in its own right: 'After being given tamoxifen (perhaps best known as a breastcancer drug) for eight days, an otherwise normally developing mouse had more than 80 percent fewer new neural stem cells in its hippocampus (a structure in the brain's frontal region linked to short-term memory).' And whereabouts in the brain is Alzheimer's first detected? In the hippocampus, I believe.