A primary neurotoxic agent in Alzheimer's disease, Impaired brain energy metabolism and oxidative stress is…

A primary neurotoxic agent in Alzheimer's disease, Impaired brain energy metabolism and oxidative stress is Amyloid-β (Aβ).
Known to rise in oxidative stress and to decrease as oxidative metabolism and NAD/NADH increase.

This study shows that B3 and nicotinamide mononucleotide (NMN) which is more expensive and not much better than good old Niacinamide is effective in increasing oxidative state and restore NAD levels.
Increasing ATP levels and lowering ROS levels.

This figure shows how B3 prevents cell death.

Aβ1–42 oligomer lowers NAD+ levels, giving B3 restores them.

And increased ATP levels.

Lowers ROS levels.