I can quite definitely tell a difference from taking this product. My memory recall is significantly better. Particularly when speaking I have noticed that "finding" the right word or name is much easier and less error prone. When taking this I have noticed that I can consume more caffeinated cofffee, which I very much enjoy, without side effects. Used to be limited to two cups a day as I would experience brain fog after three cups. Brain fog is not an issue even with five cups. A caveat for first time users, the first day I took this I experienced a mild headache. The second and third days I was quite sleepy and slept longer than normal. I believe this was due to my body "normalizing" as I had felt for a while that my sleep was not as refreshing as it was when I was younger. I believe I was "catching up" on my sleep somewhat. After the first three days I felt more energy, better focus and increased energy. I am studying to get my Instrument Rating. I definitely noticed my memory was improved comparing my results when taking the practice tests before and after using this product.