Depression rates are higher in countries with higher incomes, a study found. 121 million people worldwide suffer from depression and rates are disproportionately high in countries with higher incomes.  Depression significantly decreases quality of life and inherently comes with distorted, irrational, and negative thinking patterns. The disorder affects occupational and social functioning. Major depression is a leading cause of suicide and kills 850,000 every year.

In the U.S., France, the Netherlands, and India, depression rates stand at 30 percent are are the highest globally at 30 percent.  China has the lowest rate of major depression at 12 percent.

State University of New York at Stony Brook professor Evelyn Bromet said, "We have shown that depression is a significant public-health concern across all regions of the world and is strongly linked to social conditions. Understanding the patterns and causes of depression can help global initiatives in reducing the impact of depression on individual lives and in reducing the burden to society."

The positive relationship between depression and high incomes may be related to more work hours according to researchers. More than 89,000 people in 18 nations were interviewed and the study found that 15 percent of people in high income countries were likely to suffer from depression during their lifetime compared with 11 percent of those in low or middle income countries.

Average age of onset of depression was almost two years younger in low income countries and women were twice as likely as men to become afflicted. The death of a partner, divorce, or separation were found to be the greatest risk factors.

The study also found that dead-end jobs were more likely to cause depression than unemployment. Unfavorable working conditions including lack of health insurance benefits is also debilitating to mental health.