6. A Scanner Darkly by Philip K. Dick: Substance D
Certainly, the name of this fictional drug sounds like what frat boy calls his genitalia in a pick-up line. But in Philip K. Dick’s A Scanner Darkly, Substance D is much darker than that.
Also known as “Slow Death”, “Death” or “D”, this psychoactive drug causes the two hemispheres of the brain to act independently and often compete. Interestingly, “Slow Death” commonly used to refer to heroin in the 1970’s.
The user begins to lose touch with reality, with their own identity. Addictive, trying to wean off of Substance D, the protagonist of the story loses grip with reality, his job as an addict/narcotics agent, his mind, and eventually, himself.