For Countries, Wealth May Not Buy Happiness

"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.

Depression in Children Watch Video

Depression During Pregnancy Watch Video

Depression vs. the Blues Watch Video

"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.