updated 04/20/2011 AT 11:00 AM ET
•originally published 04/20/2011 AT 4:00 PM ET
Three months after leaving a residential treatment center, teen star Demi Lovato is bravely opening up about her private struggles – not only with anorexia and bulimia, but also with bipolar disorder.
“I never found out until I went into treatment that I was bipolar,” Lovato told PEOPLE in a candid interview that took place last month in her L.A.-area home.
But during her three-month stay at a treatment center where she underwent therapy for anorexia, bulimia and cutting, Lovato, 18, who said she’s “battled depression from a very young age,” discovered why she was having trouble controlling her emotions and actions.