Substance D Tapestry

Substance D (also called Death, Slow Death, D) is a fictional recreational drug used by characters in the Philip K. Dick novel, A Scanner Darkly. All throughout the novel, it is shown that long-term use of Substance D causes the two cerebral hemispheres of the brain to separate. "Death" also inhibits the ability of the two halves of the brain to 'communicate' with each other. This splitting of the brain (literally, right down the middle) ultimately causes a form of drug-induced Dissociative identity disorder (DID). The main character in the novel, Robert Arctor (played by Keanu Reeves in the 2006 film), had his mind divided into one side that became "Bob Arctor" and the other side that became Fred (his identity as an undercover narc.