Dementia has no effective medication to treat it, best way is to prevent from happening to you.
There are three major contributing factors for Dementia, I will list them as followings along with my opinion of how to alleviate the problem
1). Aging cause incomplete or broken communication between neurons due to degradation of certain enzymes.
Solution: Take 1/4 teaspoon of cinnamon powder daily either in capsule or powder form which will protect enzymes from degradation thus sensitize communications between neurons.
2).There are excess amount of beta-Amyloid protein in the brain for patient with Dementia, we need to minimize that.
Solution: Drink black coffee minimum 4 cups of 8 oz a day. It washes away beta-amyloid protein.
3).Feed your neurons with plenty oxygen and nutrient.
Solution: Exercise aerobic three times a week, 30 minutes each
to push blood which contains oxygen up to ends of neurons .
Also, take L-Glutamine 2x 1500mg a day which is the amino acid, nick name as " food for brain ". it acts just like glucose, directly go to feed your brain cells , so that your brain cells does not have to compete with all other organs in your body to get glucose through regular digesting process from real food.
Above are my suggestion to keep your mind sharp until THE VERY END.