Catherine Zeta-Jones (43) and Michael Douglas (68) have separated. Their publicists issued a joint statement to USA Today: "Catherine and Michael are taking some time apart to evaluate and work on their marriage. There will be no further comment." Married in 2000, they are parents of two children: Dylan, 13, and Carys, 10. Meanwhile, People reports that neither has filed divorce papers, and "those close to the couple hold out hope" the two will work things out and remain together.

It may well be that illness has taken its toll on this well-known pair whose marriage, by Hollywood standards, has not been short-lived. In 2010, Douglas was diagnosed with throat cancer, and earlier this year, Zeta-Jones announced her own month-long stay in a psychiatric hospital in order to adjust her medication for bipolar disorder. (She completed her treatment and left the hospital in less than 30 days.)

Bipolar II

Bipolar II disorder, according to the Mayo Clinic, is less severe than bipolar I, which causes severe and potentially dangerous mood swings, including both manic and depressive episodes. Bipolar II causes hypomania — a less severe form of mania — while periods of depression typically last longer than periods of hypomania. The age of onset for bipolar disorder is relatively late, around 25 years (median). The Centers for Disease Control and Prevention reports a lifetime prevalence of nearly four percent for bipolar disorder, which is more common among women than men; the ratio is approximately three to two. In most cases, treatment, which commonly consists of medication and psychotherapy, will control the disorder.

Although bipolar disorder is more common among people who have a blood relative with the condition, the exact cause is unknown. An imbalance in neurotransmitters may play a role as do environmental factors, such as stress. Although, in the past, Zeta-Jones has publicly stated she intermittently seeks professional care to keep her condition in check, she has indicated stress due to her husband’s illness may have triggered the condition most recently.

Throat Cancer

Throat cancer, according to the National Cancer Institute (NCI), forms in tissues of the tonsils, the larynx (‘voice box’), or the pharynx, which is the tube inside the neck that starts behind the nose and ends at the top of the windpipe and esophagus. NCI estimates there will be 12,260 new cases of laryngeal cancer and 13,930 new cases of pharyngeal cancer in the U.S. during 2013. Additionally, NCI predicts that 3,630 will die of the former and 2,400 of the latter, within that same time span. Treatment commonly includes surgery, chemotherapy, and radiation.

USA Today speculates that Douglas's recent comments about human papillomavirus (HPV) possibly causing his throat cancer may have displeased his wife as he later issued a statement explaining he was not implying he got it from her. Douglas's comments aside, researchers have found that life-threatening illness creates severe stress that may result in marital discord, separation, or even divorce. But there's one caveat: only if the cancer patient is female.

Published in Cancer, the study, which tracked 515 patients, found divorce or separation occurred at a greater than six-fold increase after diagnosis when the affected spouse was the woman.

Source: Glantz MJ, Chamberlain MC, Liu Q, et al. Gender disparity in the rate of partner abandonment in patients with serious medical illness. Cancer. 2009.