(CBS) Charlie Sheen may or may not have bipolar disorder, but new research suggests that the potentially deadly mood disorder may be more prevalent in the U.S. than in other countries.
A survey of 61,000 people in 11 countries showed that 4.4 percent of Americans have the disorder, which is characterized by shifts in mood from deep sadness to an almost euphoric state called mania.
What about other countries? India has the lowest rate of bipolar disorder, with 0.1 percent of its population affected. Other countries cited in the survey included Columbia (2.6 percent) and Japan (0.7 percent). Worldwide, 2.4 percent of the population is bipolar, according to the survey, which was published in the March issue of Archives of General Psychiatry.
Exactly why Americans are more vulnerable to bipolar disorder, a.k.a. manic depression, isn't quite clear.
Wealth may be one factor, researchers say. In general, bipolar was shown to be more prevalent in the high-income nations, with Japan the lone exception. But our openness about our emotional issues may also mean that Americans are simply more likely to get a proper diagnosis.
"Cultural awareness plays a very big role in psychiatry," Dr. Sara Bodner, assistant professor of psychiatry at the University of Miami School of Medicine, told CNN. "Some cultures have a huge reluctance to speak about psychiatric things."
Whatever the reason, it's clear that bipolar disorder takes a big toll on Americans' health. Without appropriate treatment - often antidepressant medication in conjunction with counseling - the shifting moods and energy levels, distractibility, restlessness, disturbed sleep, and other hallmarks of the illness can affect relationships, job performance, and even the ability to carry out day-to-day tasks.