It's too early to say if such linkages will pan out. My grandfather is 78 years old. He has a drooling problem due to a stroke and Alzheimer's. D.H. Drooling can be a consequence of some strokes that affect a person's ability to swallow saliva. A stroke is only one example of the many causes of drooling.
Medicines can stop saliva production.
Atropine and scopolamine can dry saliva production. Scopolamine is available as an adhesive skin patch. Unfortunately, both medicines can further cloud the mind of an already-clouded mind. Your grandfather might not be able to tolerate either. Those measures sound like overkill, but they are actually quite simple procedures.