(CNN) More than a quarter of medical school students report depressive symptoms or depression, while about one in 10 experiences suicidal thoughts, according to a new analysis in the Journal of the American Medical Association . The analysis reviewed nearly 200 studies involving more than 129,000 students in 47 countries.

Depression is "an open secret" in the profession, said Dr. Douglas Mata, co-principle author, a resident physician at Brigham and Women's Hospital and a clinical fellow at Harvard Medical School.

These calculations are more than just numbers to co-principle author Dr. Srijan Sen.

"When I was a medical student, a couple of people just a little bit older than me really suffered with depression and had serious suicide attempts, and one of them completed suicide," said Sen, a professor of depression and neurosciences at the University of Michigan. "It hit home to me and made me realize how big a problem this was and was part of the reason why I got involved in this research."

A worldwide problem

Mata, Sen and their colleagues searched databases for published studies reporting the prevalence of depression in medical students. All the studies but one relied on surveys in which students reported their own symptoms.

"There were several hundred individual studies of smaller groups of students that were out there, but each on its own is not that impactful," said Mata. "I thought by combining everything and saying, 'listen, this is a study with over 120,000 people in it; this is something we're seeing around the world,' it kind of underscores how serious this is."

The Diagnostic and Statistical Manual of Mental Disorders defines "major depressive disorder" based on nine cardinal symptoms to be diagnosed during an in-person interview. Technically speaking, the surveys (which probe for these symptoms in a standardized fashion) cannot diagnose depression, said Mata. But each survey had been validated in prior studies and shown to agree with interview-based diagnoses.

"That's why we trust the data that we were able to put together," Mata said, noting that surveys also offer the benefits of anonymity. Since there's still some stigma associated with mood disorders, medical students are more likely to be honest about their symptoms if they don't have to worry about their attending physician or the medical board finding out their responses.

Mata said he was motivated by the need to provide data for policy-makers on just how widespread the problem is among future doctors, so perhaps they can try to reverse these statistics.

High rates of depression

Overall, the researchers calculated the prevalence of depression or depressive symptom as nearly 26.7%, with exactly 37,933 of 122,356 total participants reporting symptoms. A subset of 24 studies from 15 countries looked at suicidal thoughts; here the overall prevalence was 11% (or 2,043 of 21,002 participants), say the researchers.

With some variation across regions, then, medical school students are between two and five times more likely to experience depression than the general population of the United States.

Sadly, the study also found that the percentage of students who see a doctor about their depression is low: just 15.7%.

Last year, Mata, Sen and their colleagues published a related paper focusing on depression in medical residents.

"Taken together, these two papers paint a full picture of the life cycle of mood disorder and wellness from the beginning of medical school to the end of residency. The two studies in combination serve as an impetus for educators and policy-makers to take this problem seriously," Mata said. "What is it about the medical school environment that is leading to these adverse outcomes?"

Though his research does not answer this question, clues can be found in the real life experiences of one medical student.

'Prognosis Poor'

"I was taking care of eight patients in the hospital. One woman was very sick having on and off respiratory failure, and I was concerned about her. One morning I walked into her room to find that her lips had turned blue," wrote Dr. Frances Southwick in her book " Prognosis Poor ," an account of her medical training.

After reviving the patient and calling for help, Southwick was chewed out by a nurse and then again by a senior physician, who said, "Your poor planning ain't my emergency." This same doctor took a break before helping the patient, who died eight days later. Southwick felt angry and helpless.

As her residency progressed, Southwick says, she began to experience intense depressive symptoms, including feelings of worthlessness. She became confused and irritable. Her mistakes increased; the pace of her work slowed.

Sleep deprivation worsened her symptoms: "It's literally used as a torture method in a lot of countries," she said. Meanwhile, she said, she was giving "150% at work," and although she tried to maintain her personal relationships, her support system took a hit, too.

Training to become a doctor requires a skill set that goes far beyond book smarts, explained Southwick: You need to learn about hierarchy and psychology.

"There's this phenomenon called pimping: It's a universal medical term that sounds like slang, but it's well-accepted as a term," she said. "It means a senior physician asking a junior physician questions about medical topics, usually in front of his or her peers, and sometimes it is meant for actual medical education, but often, it's used as a way to enforce the hierarchy.

"You never know if you're going to be the one targeted in a pimp session," Southwick said. Residents change jobs every four weeks -- one month in obstetrics followed by one month in surgery, for example -- and this too creates "amazing amounts of anxiety."

"You kind of have this sense of 'If I speak out or I screw up rotation or whatever, I could be kicked out of the program,' " she said. If that happens, she explained, you won't become a physician, and you'd be stuck with $250,000 in debt.

Fearful and exhausted, in an environment where speaking up is discouraged, her symptoms of depression climaxed in a suicide attempt. With the help of a faculty member who prescribed antidepressants after noticing her failing mood, Southwick muddled through the remainder of her residency.

Today, Southwick is in her fourth year of practice in family medicine and doing well, thanks in part to therapy. She believes that structural changes need to be made to the medical education curriculum while psychotherapy should be routine for all students.

"Everybody suffers," she said, adding that even medical students who don't become depressed "develop some level of burnout or some level of poor functioning related to job stress."

Systems and stressors

Mata agrees, noting that the focus is placed on individual students or residents when systemic issues are the root cause.

Many students move to new cities to fulfill residency requirements. In their new homes, they lack friends for support while facing chronic sleep deprivation and becoming exposed to high-intensity situations involving critically ill or dying patients.

"Before students start medical school, their quality of life is higher than that of age-matched peers, but after they start, their quality of life quickly becomes lower," said Dr. Joan Meyer Anzia, residency program director at Northwestern University/Feinberg School of Medicine. Anzia was not involved with the current study.

Sadly, the problem doesn't stop when school ends. "Physicians suicide more than people in any other profession," Anzia said.

Although the newly published study has statistics that were not previously known, the problem among physicians is. The Accreditation Council for Graduate Medical Education, with help from the American Foundation for Suicide Prevention and the Mayo Clinic, has created a campaign to provide support to medical students and doctors. The resource page, which shares information about programs and resources, even includes recommendations for how training programs should respond if a resident dies by suicide.

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Meanwhile, mood disorders like depression are not taken seriously enough, added Mata.

"In my opinion, I don't think we should look at depression and other psychiatric illness as quote-unquote 'psychiatric illnesses' because they're also medical illnesses," Mata said, explaining that the brain can have problems just like any other organ.

Taking a different perspective on the study results, Sen believes some of the new insights gained from studying physicians in training might help other people.

"Military populations, women in the peri- and postpartum period, people taking care of sick parents and primary caregivers -- all of these groups have high rates of depression, PTSD, anxiety or other mental illnesses related to stress," explained Sen. "Maybe some of the factors that we find in physicians will carry over to these other populations."