July 26, 2011 -- The old adage that money can't buy happiness may be true not only for individuals, but for society as a whole, according to new international research on depression.
In a global collaborative study that looked at depression and social conditions in 18 countries, researchers found that while depression has a similar debilitating effect on people worldwide, wealthier nations tend to have a higher incidence of depression among their citizens when compared with middle-income or poorer nations.
Researchers interviewed 89,000 people from countries ranging from high-income nations like France, Germany, Belgium, the United States and Japan, to low-income ones like Colombia, India, China, Mexico and South Africa. On average, 15 percent of the population in wealthier nations suffered from depression over the course of their lifetime as compared with 11 percent for the less wealthy nations.
The United States and France were the leading most-depressed nations, with a prevalence of depression five times what was reported for less wealthy nations like Mexico and China.
"We were struck by the difference among high-income and low-income countries," says lead author on the study Dr. Evelyn Bromet, a professor of psychiatry at State University of New York at Stony Brook. "Why this may be the case is the $64,000 question. We don't know for sure."
One of the things Bromet and colleagues found most striking however, was the extent to which people from all different nations seemed to respond to depression with similar levels of impairment -- that is, depression negatively affected citizens' ability to work, have meaningful relationships and in general live their lives, whether in Ukraine or in Japan.
Happy Lives on More Moderate Incomes
It is impossible to tell exactly how or why a country's wealth may have a negative impact on its citizen's happiness from this research, but mental health experts have a few ideas as to what might be going on here.
"Wealthier nations ... are industrialized nations where individuals rely less on family support for everything from childcare to marital advice. There is a well known link between social support being a protective factor against depression," says Dr. Sudeepta Varma, assistant professor of Psychiatry, NYU Langone Medical Center. "I also believe that poorer nations may look to religious/spiritual beliefs for comfort, also a protective factor."
On the other hand, it could have to do with expectations for success and wealth, says Dr. Gary Kennedy, director of the Division of Geriatric Psychiatry at Montefiore Medical Center.
"There's a greater disparity of wealth in higher income nations, so part of what happens is that your expectations are greater. In a sense, you have farther to fall than one might have in a lower-income country," he says.
Yet another possibility, noted by the authors, is that using interviews to gauge depression may be underestimating incidence of the condition in nations where mental health isn't something that's discussed openly with a foreign interviewer.
"The strength and the weakness of our study is that we used the same interview everywhere," Bomet says. While this makes the data consistent, it may not capture depression as well in lower-income countries where mental health is less widely discussed.
"In the U.S. people are so used to being interviewed, where as in Ukraine, for instance, no one has ever done a study like this before," she says. "We used an American/European approach to defining depression. It's possible that the instrument was more sensitive in the U.S. and that we missed some aspects of depression in say, Asian cultures."
Though the connection between the prevalence of depression and the wealth of a nation is not well understood, this research serves as further evidence that cultural sensitivity is pivotal when dealing with global mental health issues.
"A person's culture and nation of origin is going to have an impact on the nature of their depression, and we need to approach treatment with culturally sensitive questions," Kennedy says.