The 20-year-old singer-actress, who has battled personal issues for years and spent months in rehab following a meltdown on tour in 2010, said she was a strange child who used to worry people with her dark thoughts, reported Daily Star.
"The principal called my parents and made me sign this suicide contract saying that I would not kill myself," she said.
Shortly after her rehab stint, the 'Skyscraper' hitmaker said she was a survivor of bulimia and self-harming, and also battled with bipolar disorder.