I might sound like a broken record, but dentistry is stuck in the past.

Alzheimer's is basically an advanced form of gum disease caused by Porphyromonas gingivalis) that has infiltrated into your jaw and then traveled into your brain where it causes systemic inflammation which in turn lets other pathogens in that cause neurodegeneration.

There is probably no cure because the only thing you can do in dentistry is prevention and preventative dentistry is still in its infancy.

This is probably wasted on the HN crowd though, because I haven't seen any demand for preventing Alzheimer's.