Rates of depression are higher in countries with higher per capita incomes. 121 million people worldwide have depression. Severe depression can lead to suicide and causes 850,000 deaths every year. The United Sates and France had the highest depression rates. Higher incomes can be related to more work hours and a lowered quality of life. 15% of people in high-income countries were likely to become depressed during their lifetime, compared with 11% of those in low or middle-income countries.
British Medical Journal, Aug 2011