@abid These are anecdotal observations and not backed by any scientific evidence. The long term safety and risk of drug interactions are unknown. AARP is concerned about the misleading and unsubstantiated claims by the makers of Prevagen:

"Last year, the Federal Trade Commission (FTC) and New York’s attorney general sued Quincy Bioscience for false advertising in federal district court in New York. The case was dismissed but is being appealed to the Second Circuit Court of Appeals.

“The statements Quincy Bioscience makes to sell Prevagen — that it treats memory loss — are unsubstantiated and misleading,” said Julie Nepveu, a senior attorney with AARP Foundation Litigation, which filed the brief on behalf of AARP and the foundation." (from the AARP website).