You have a good point
However, it's baby steps. Research builds on research until one day, this little bit of research could actually lead to a cure. So, in the meantime, do we extend the misery for current Alzheimer's patients? Maybe this should be added to living wills: If diagnosed with Alzheimer's and anything short of an actual cure is offered, I choose a. to allow the disease to progress normally or b. avail myself of anything that may further research and possibly extend my life.
This is not a decision one wants to leave up to a caregiver. It would be an agonizing one for the caregiver.