My boyfriend and I didn't take this supplement long enough to ascertain its effectiveness. Reason being, it made us very drowsy. We thought taking it at night would be alright, but upon waking up in the morning, we still felt drowsy. And the drowsiness would persist for some hours. Not sure what was happening.. I bought this because it was stated that the formulation used is the same as that used in clinical trials.
I'm just continuing many years of use of PS without having any objective reason to believe it's better than other products now advertised aggressively. Subjectively, I have the impression that memory capacity is maintaining, at least (except for names, which I've been brain dead on since my late teens.) If the price of PS goes up, I'll have a glance at the new products.