Depressive disorders erode quality of life, productivity in the workplace, and fulfillment of social and familial roles. In today's knowledge- and service-driven economies, the population's mental capital (ie, cognitive, emotional, and social skills resources required for role functioning) becomes both more valuable and more vulnerable to the effects of depression. Depressive disorders, severe mental illnesses that should not be confused with normal mood variations, are part of a vicious circle of poverty, discrimination, and poor mental health in middle- and low-income countries. These realities also have major economic ramifications: treatment costs of depression are soaring but are only a fragment of the costs of reduced productivity due to depression.
More than half of those with depression develop a recurrent or chronic disorder after a first depressive episode and are likely to spend more than 20% of their lifetime in a depressed condition. With a 12-month prevalence rate of more than 5% in most high-, middle-, and low-income countries and its occurrence at almost any age,3 depression generates substantial loss of quality of life and personal morbidity and despair. But it also leads to considerable additional damage through biological sequelae and maladaptive illness behaviors, thus increasing risk of cardiovascular disease, dementing illnesses, and early death while amplifying disability, complications, and health services use in those with coexisting chronic illnesses. Depression ranks third among disorders responsible for global disease burden, with all the concomitant economic costs to society, and will rank first in high-income countries by 2030.