Prevagen is a health supplement that has shown positive effects related to memory. Users have felt better retention. The results may vary from one person to another. It may take a couple of months to show results in a few cases. It is a non-prescription natural nootropic that can be bought over the counter as a dietary supplement. You must not mix the dosage with other similar supplements without consulting a doctor. Prevagan has been in the market since 2007 and is still holding a strong hold among the aging mass.