There is a lot of wiggle room with the word constant.
Constant in that an addict is always an addict with his brain chemistry changed?
Constant, that a kid who does drugs a month in school will be an addict for the rest of their life?
Constant, meaning it is at some level always with us like crime and war?
Constant, in that law enforcement will always have to go after bad stuff to keep numbers down from what they might become without it?
All depends what the context of CONSTANT would be.
I think 3 of the 4 I gave as examples are true for the most part.