The non-modifiable factors of age and family history are much much the stronger. (They didn't need to wait decades to have a study to discern those; they are obvious.)

For contrast, see:

NIH state-of-the-science conference statement: Preventing Alzheimer's disease and cognitive decline (2010) - https://europepmc.org/article/med/20445638

Currently, firm conclusions cannot be drawn about the association of any modifiable risk factor with cognitive decline or Alzheimer’s disease.