Cumadin (warfarin) anticauglant act by disabling vitamin k/k2, in other words by creating K/k2 deficiency, thus prevent/reduce clotting. As K/k2 are needed for proper brain function, and as Cumadin is widly used, this is a concern
review of current evidence linked below
Source: The Relationships Between Vitamin K and Cognition: A Review of Current Evidence – PMC