I tried Niacinamide (500mg 2x/day) months ago and noticed absolutely no improvement in my memory.
I even tried the 1,500mg timed-release 2x per day as someone else posted, with no improvement either.
After reading the claims, I was so optimistic. :(
I've also tried Lion's Mane and Taurine, both separately and together and experienced some (slight) improvement, but not enough to continue taking them, since they were expensive.