More people reported being depressed in France and the U.S. than anywhere in the world, according to interviews of more than 89,000 people in 18 different countries.
The study, sponsored by the World Health Organization, found that 21 percent of people in France and 19.2 percent of people in the U.S. reported having an extended period of depression within their lifetime. On average, 15 percent of people in high-income countries reported having an episode, compared with 11 percent in low-income countries, according to the study, published July 25 in the journal BMC Medicine.
Depression affects nearly 121 million people worldwide and is the second leading contributor to shorter lifespan and poor health for individuals 15-44 years of age, according to the Geneva-based WHO. The higher percentage of depression reported by people in wealthier countries may reflect differences in societal expectations for a good life, said study co-author Ronald Kessler.
“There are a lot of people in the U.S. who say they aren’t satisfied with their lives,” Kessler, a professor of health care policy at Harvard Medical School in Boston, Massachusetts, said in an interview. “U.S. expectations know no bounds and people in other countries are just happy to have a meal on the table.”
The disease is the third-largest contributor to lowered productivity in the workplace, Kessler said.
Researchers took into account both clinical depression, a biological condition that leads to low self-esteem and loss of interest in otherwise enjoyable activities, and types of mild depression, which can be situational or caused by environmental influences. The latter was likely the cause of higher rates in the U.S. and France, Kessler said.
“There’s no change in biological depression, but what’s going up is the more mild depression,” Kessler said. “Objective things haven’t changed. We have an expectation that everything’s going to turn out perfect but it doesn’t.”
Scientists from twenty different institutions worldwide worked with the WHO’s World Mental Health Survey Initiative, obtaining data by interviewing 89,037 people in 18 different countries from 2000 to 2005. Trained interviewers spoke with respondents in person or over the phone about traumatic events in that person’s life, substance abuse, relationships, happiness, and other factors that could influence mental health.
The report also found that women were twice as likely to experience depression, and the strongest link to depression was separation or divorce from a partner.
“Most people that come out of medical school or residencies do not learn about depression, so they don’t know how to recognize it,” said lead researcher Evelyn Bromet, a professor and epidemiologist at Stony Brook University Medical Center in Stony Brook, New York.