updated 11/26/2013 AT 2:30 PM ET
•originally published 12/02/2013 AT 9:00 AM ET
Lovato, 21, who ended up in rehab in 2010, admits that since she had grown-up responsibilities, she thought she could act like a grown-up, too.
“My parents tried to control me, but I’d be like, ‘Oh really, I’m grounded? Well, I pay the bills,’ ” she says. “They did the best they could. And I think that’s why a lot of young stars struggle when they’re making money or providing for their family.”
“My mentality was ‘Work hard, play hard,’” she admits in the magazine’s Dec/Jan issue. “It was hard to listen to the word ‘no.’ I wanted to make my own rules. I thought that if I was adult enough to get there, then I could party like an adult. And obviously, I couldn’t.”