A lot of things can actually be contributed to a messed up spine. I used to work at a Chiropractor and pretty much everything you do in life, including sleeping, walking, even being born, can cause your spine to start forming wrong. I wouldn't be surprised if this girl's spine deformity formed apart from her drug use and would have formed anyway had she not done drugs, but she just attributed it to that because it's an easy scape goat.
That said, long nights of drug use, dancing for hours, laying in odd positions in cuddle puddles and other abuses of your body would definitely have an impact on the bones in your spine. When I still worked at said Chiropractor, ever day after I went out dancing my spine would need quite the adjustment and my doctor/boss could tell right away that I was out all night partying. :D
