Demi Lovato sympathizes with Hollywood actress Catherine Zeta-Jones' bipolar battle - because the teen star suffers from the disorder too.

The former Sonny With A Chance actress heaped praise on Zeta-Jones last week after it emerged the Oscar winner had undergone treatment at a mental health facility in Connecticut to combat a serious bout of depression.

In a post on her Twitter.com page, Lovato wrote, "I don't know Catherine Zeta-Jones personally but what she has decided to do... SO brave... and SO difficult but worth it... I'm proud of her."

Now Lovato has revealed she, too, has been diagnosed with the condition - doctors made the discovery last year when she checked into rehab to deal with "emotional and physical" issues linked to an ongoing eating disorder.

She tells People magazine, "I've battled depression from a young age. I never found out until I went into treatment that I am bipolar. At first, I was like, 'What does that even mean?' But looking back, it makes sense... That's why I wasn't happy when everything in my life was great."

But Lovato insists she has the issue under control with the help of prescription drugs.

She adds, "I'm being treated for it with medication and therapy."

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