> … similar related drugs like dextromethorphan and ketamine and other NMDA receptor antagonists are innovative drugs to help prevent Alzheimer's.

Should read “NMDA receptor antagonists _may_ give rise to treatments that _may help prevent or ameliorate the symptoms_ of Alzheimer’s.

Nobody even knows how Alzheimer’s works at all — like most diseases it’s a description of some detectable symptoms, some of which could even turn out to be the body defending itself.

Thus compounds that may have a mechanism of action that affects some concomitant, visible symptoms might potentially be useful.

The use of definitive sentences about unknown results is how we end up with wellness and some “biohacking” nonsense.