'The X Factor' USA judge - who has struggled with cutting and bulimia in recent years - says landing a role singing the theme tune on children's television show 'Barney & Friends' as a child cemented her issues with self-esteem and depression, but her suicidal thoughts had already started at the age of seven.
The 19-year-old singer told the July issue of Cosmopolitan magazine: "At the time, I was just so grateful to be on TV, but I was also really struggling. Even before 'Barney', I was suicidal. I was seven.
"I've talked about being bullied and the years of being a teenager, but I went through things when I was younger that I've never talked about that probably caused me to turn out the way I ended up turning out."
Demi also admits her new album's most personal ballad, 'Warrior', is far too painful to talk about, although she hopes to one day be able to discuss the traumatic events of her youth which inspired the song.
The lyrics read: "There's a part of me I can't get back/A little girl grew up too fast/All it took was once, I'll never be the same/Now I'm taking back my life today."
The singer explained: "My family knows what it's about. When I'm ready to open up that subject with the outside world, then I'll be free to talk about it. But right now, it's kind of one of those things where the lyrics speak for me. It's all in the song."
Demi previously shockingly revealed she was forced to sign a no-suicide contract by her school at the age of seven because her teachers worried she would take her own life.
She said: "The principal called my parents and made me sign this suicide contract saying that I would not kill myself. They weren't expecting that so young."