There’s nothing new about lean/barr/purple drank/syrup. People have been misusing codeine for a long time and the resurgence of its use in Houston started in the late 1980s.
What’s interesting about this is this “screwed culture”, in which codeine cough syrup is central. It has its own music, language, clubs, etc. It has a lot of parallels with the psychedelic acid subcultures of the 60s.
It’s a great example of a tribe within the culture of addiction.