The 21-year-old actress thinks her battle with depression was triggered after she was tormented at school by other kids for having a skin condition.
Speaking in the May issue of the US Elle magazine, she said: "I went through a time where I was really depressed. Like, I locked myself in my room and my dad had to break my door down.
"It was a lot to do with... I had really bad skin and I felt really bullied because of that.
"But I never was depressed because of the way someone else made me feel. I just was depressed."
Meanwhile, the 'Wrecking Ball' hitmaker has been struck with grief over the past week after her dog Floyd, which she rescued in 2011, passed away last Tuesday (01.04.14).
The blonde beauty posted a series of distressing messages on Twitter last weekend after she was presented with a new puppy, which she named Moonie, by her mother Tish.
She wrote: "I wanna sleep but all I can do is cry I never wanna go home to a house where Floyd isnt running & playing how do I get thru this
"I feel physically sick & I am so emotionally and physically exhausted I feel like I have nothing else to give sweet baby Moonie
"Maybe I'm not ready yet.... But being alone won't bring him back to me..... I'm at a loss I don't know what to do (sic)".