Jamie McCarthy / WireImage 1 / 5
Jamie McCarthy / WireImage 1 / 5

By Jen Odell

Between checking herself into a psychiatric clinic and being teased mercilessly in the press for her ... unique fashion sense, Mischa Barton has had a tough run of things since the beginning of 2009.

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"That was a tumultuous year. It was one thing after another, and it led to a pretty reasonable breakdown," she tells the U.K. edition of OK! Magazine for its latest issue (via ONTD).

"I suffer from depression and that's the truth. I've never told anybody that."

Barton, whose career has faltered somewhat since her "O.C." heyday, is quick to point out that dealing with depression doesn't mean she can't deal with life.

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"I am by no means mentally unstable," she says. "Well I am pretty crazy and weird sometimes, but not mentally unstable."

The 24-year-old actress, who has been dating British DJ Ali Love for the better part of a year and has a few film projects in the hopper for 2010 and 2011 release, tells OK! that staying positive is what keeps her going.

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"I balance [depression] with positive things in my life and that's why I have my outlets of music and literature," says Barton. "As much as I get down, I'm an upbeat person. People always think of me as kind of a light in a room. I love to make people laugh."