i got this question right but why couldnt it be ginko biloba?

The researchers found that people who participated in mentally challenging activities most often, both early and late in life, had a slower rate of decline in memory compared to those who did not engage in such activities. Even when people had plaques and tangles and other signs of damage to their brains, mental stimulation seemed to help protect memory and thinking skills, accounting for about 14 percent of the difference in decline beyond what would be expected (Prashanthi Vemuri, PhD, Elizabeth C. Mormino, PhD: “Cognitive Stimulating Activities to Keep Dementia at Bay.” Neurology, Vol 81. 2013)

also the way i see it, AD pts have problems with hippocampus (i.e. short term memory power house) so keeping notes and lists or whatevvaa might help slow their cognitive decline as theyll be keeping the hippocampus more active