Do you know ghouls from goblins and ghosts?
1956, from psycho- + Greek -tropos "turning," from trepein (see trope). Hence, what "turns" the mind.
psychotropic psy·cho·tro·pic (sī'kə-trō'pĭk, -trŏp'ĭk)adj. Having an altering effect on perception or behavior. Used especially of a drug. n. A psychotropic drug or other agent.