Mindrot is a rare disease that affects and attacks the mind, present in human society for thousands of years so far. The earliest known affliction of Mindrot is a cave painting in middle Valdar depicting what appears to be a demon attacking the mind of a vaguely humanoid figure, though many in the academia scene doubt this as sufficient proof of Mindrot dating back to the early Wild Era.
Mindrot attacks the memories and motor functions of a person, slowly stripping them away piece by piece. When people afflicted with Mindrot go to sleep, when they wake up, they will find that they have forgotten some of their own memories. There are no limitations to what can be forgotten, only that large chunks will disappear overnight. Worse still is that if Mindrot goes on for long enough, other people will begin to forget about the afflicted themselves. The length of Mindrot affliction (from first diagnosis to death) ranges from a week or two or several months. There is no cure for Mindrot that has been discovered yet.
To boot, there has never been a stage of completion for Mindrot. Those afflicted with Mindrot will always die before the disease reaches its theoretical zenith. No common thread has been discovered between these deaths.
Mindrot is caused by The Boogeyman, a creature in the collective human consciousness that will break into the minds of those sleeping and begin to feast on their soul until there is nothing left. This is what causes the degradation of memories and eventually causes everyone to forget the afflicted. There is never a person that reaches the end of Mindrot because they are forgotten.