Catherine Zeta-Jones voluntarily checked herself into a rehab center for issues related to her bipolar II disorder.

She released a statement on Monday via her publicist about her decision to seek treatment. It is expected to be a 30-day program.

"Catherine has proactively checked into a health care facility," her rep, Cece Yorke, told People. "Previously Catherine has said that she is committed to periodic care in order to manage her health in an optimum manner."

A source close to the actress denied that there had been any drastic change in her condition. The insider said the 43-year old, who is married to Michael Douglas, simply wanted doctors to monitor her status.

"There was no big problem," a friend said. "This was just a good time to do it. She is in between projects. This has always been part of the plan. She would manage her health. She is vigilant about it."

Zeta-Jones was last publicly seen on April 22. She and Douglas walked the red carpet at the 40th Anniversary Chaplin Award Gala at Lincoln Center where Barbra Streisand was being honored. The couple was all smiles and gave no impression that anything was wrong. Douglas declared that he was having a perfect night out with his wife.

"Oh yes. Yes, this is pretty cool," he said.

However, Zeta-Jones was not by his side for the White House Correspondent's Dinner on April 27. By Monday, the reason for her absence was explained.

This is not the first time that Zeta-Jones has sought help for her mental condition. In 2011 she revealed she was diagnosed with bipolar II disorder. At the time the mother-of-two checked into Silver Hill Hospital, a mental-health facility in New Canaan, Conn. She opened up about the experience to People.

"This is a disorder that affects millions of people and I am one of them," she said. "If my revelation of having bipolar II has encouraged one person to seek help, then it is worth it. There is no need to suffer silently and there is no shame in seeking help."

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