Nearly one-third of doctors in the early stages of their careers screened positive for depression or had symptoms during their medical training, according to a comprehensive international review released Tuesday.

Researchers said the prevalence of depression was much higher among medical residents than the general population. They focused on the years of internship and residency, which come right after medical school and are marked by long hours, intense on-the-job training, high levels of responsibility for patient care but low rank within a medical team.

The findings, published in JAMA, are based on an investigation of a half-century of peer-reviewed studies from around the world that looked for depression symptoms in more than 17,500 medical residents.

In their analysis, researchers found that the percentage of residents with possible depression ranged from 20 percent to 43 percent. On average, when all data were equalized and tallied, they concluded that 29 percent of physicians-in-training had depression or depressive symptoms. They found no statistically significant difference among the prevalence estimates in U.S. studies vs. elsewhere, or between medical specialties, or between men and women.

But as one point of comparison, the National Institute of Mental Health has said that in 2013, about 6.7 percent of all U.S. adults had at least one major depressive episode during the previous year.

The review team was led by Douglas Mata, a resident doctor in pathology at Brigham and Women’s Hospital in Boston, and Srijan Sen, a University of Michigan Medical School psychiatrist who specializes in physician mental health.

In an interview, Mata said many of the doctors covered by the studies fell short of meeting all criteria for a diagnosis of major depressive disorder. But the distinction between symptoms and disease are not that important.

"You can have significant symptoms that are just as debilitating even if you don't meet all the criteria," he said.

The implications for patients also are important. Depression among residents has been linked to poor-quality care and increased medical errors.

There was a small but statistically significant increase in the rate of depression over the five decades covered by the review.

"The increase in depression is surprising and important, especially in light of reforms that have been implemented over the years with the intent of improving the mental health of residents and the health of patients," said Sen, who is also a member of University of Michigan's Depression Center.

Several factors appear to be at work.

The practice of medicine today is radically different from that of 20 to 30 years ago. Shorter hospital stays require protocol-driven procedural care "with little opportunity for thinking and learning," according to a JAMA editorial accompanying the review. Added pressure comes from online ratings of doctor performance, and direct-to-consumer advertising causes "patients to demand medications for conditions they sometimes do not even have," the editorial said.

There is also a huge disconnect between what happens in medical school and what actually happens in the first years of residency, Mata said.

New doctors are "spending 40 to 50 percent of their time on the computer” doing secretarial work, he said. Very little time is spent by the bedside. “It’s not rewarding."

University of Nevada medical school dean Thomas Schwenk, who penned the editorial, said the findings were alarming and showed a deep-rooted problem that requires a fundamental overhaul of the current training environment.

"The personal and professional dysfunction, not to mention the suicide rate that may derive from this symptom burden, should be disturbing to the profession," Schwenk wrote. "These findings could be easily construed as describing a depression endemic among residents and fellows."

Although the medical profession says it recognizes the importance of health and wellness, the value system of the current training environment makes clear to residents that it's unacceptable to stay home when sick or to ask someone to cover for them when a child or parent is in need, or simply to "express vulnerability in the face of overwhelming emotional and physical demands," Schwenk wrote.

Residents are afraid that any record of mental health care could compromise future training, medical staff membership and licensing, he noted.

Solutions fall into three categories, he suggested: Provide more and better mental health care to depressed physicians and those in training. Limit the trainee's exposure to the training environment. Consider fundamental change to the medical training system.

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