For age 92 I am quite well, considering. I am a college grad, in the work place since 1952, and on the road 84 years. Now live alone, no problem. Memory? Many, and only slipping a little. I take your product daily to keep sharp enough for life, How can I honestly rate the efficiency of the product? Since I maintain my level of cognisance to be socially fit, still play musicial instruments, self-maintain, I'd say something is doing right. I would be remiss if I did not give your product adequate credit.