Theoretically Pure Anterograde Amnesia is the fourth studio album by the Caretaker, an alias of musician Leyland Kirby. Released in 2005, it abandoned the haunted ballroom aesthetic of the previous albums and explored memory loss. Divided into six CDs, its drone tracks combined create a five-hour long release. It was compared by several critics to other musicians, including Merzbow, Boards of Canada, and Krzysztof Penderecki.