What is the theme of crank by Ellen Hopkins?

Crank is about a girl named Kristen who goes and visits her father and meets this guy named Brendan and he gets her into crank (Monster) she then begins to become Bree she then realizes what sexy is. she goes through living to her parents to sneak out and fall in love with someone who is into the drug. she ends up getting pregnant and decides to keep the baby.

the other books get better and better, she has many struggles in her life but this book is a true story about Ellen Hopkins daughter and having to go through this.