Demi Lovato refuses to blame the "meltdown" she suffered last year (10) on a break-up, insisting there were underlying issues behind her depression.

The singer lost her temper and struck back-up dancer Alex Welch in the middle of a flight last October (10), before pulling out of a world tour with the Jonas Brothers and checking into rehab to deal with "emotional and physical issues".

It was rumoured that Lovato was struggling to deal with her split from Joe Jonas and had lashed out at Welch in a jealous rage.

But the star admits mounting pressures in other areas of her life prompted the altercation.

She tells Elle magazine, "When you punch someone on a plane, enough is enough. I just felt like she betrayed me. That's the bottom line.

"I was completely out of line all summer. Just the worst attitude - totally ungrateful. (But) I wouldn't credit my meltdown to a guy. There was so much other stuff in my life."

The 19 year old sought treatment for depression and an eating disorder, and was subsequently diagnosed with bipolar disorder.