She couldn't be, it would be a lot more noticeable, she wouldn't be so awkward and shy around people. I mean look at Paula Abdul, Amy whinehouse, and even Lindsay lohan around their period of drug use. It's obvious, they behave absolutely insanely. Where as Lana is a very timid well behaved girl. It would certainly be noticeable if she was on any heavy drugs, (not including marijuana because she would continue to be mellow, plus it wouldn't have any physical effects on her appearance).