A study published this week in PLOS Medicine reports the most recent and comprehensive estimates on how much death and disability is attributable to depression, both worldwide and in individual countries and regions. When compared to other diseases and injuries, major depressive disorder ranked as the second leading cause of global disability and eleventh leading cause of global burden in 2010.
Rates and ranking among all causes of disability varied by country and by region. The rates are highest in Afghanistan and lowest in Japan, and depression ranks first in Central America and Central and Southeast Asia. Disability from depression affects mostly people in their working years, and women more than men.
To arrive at the estimates, the authors of the study, led by Alize Ferrari, University of Queensland, the Queensland Centre for Mental Health Research, Brisbane, Australia, compiled relevant information from all published research studies on major depressive disorder, also called clinical depression, and dysthymia, a milder chronic form of depression.
They then used mathematical tools to estimate a standard measure of disease burden: “disability-adjusted life years” (DALYs), calculated by adding together “years lived with a disability”, (YLDs) and “years lost because of disease-specific premature death” (YLLs). For some countries and regions, especially low-income countries, few studies had been published, and the researchers had to substitute actual numbers with reasonable estimates to calculate YLDs and DALYs.
When compared to other diseases and injuries, major depressive disorder ranked as the second leading cause of global disability (or YLDs) and eleventh leading cause of global burden (or DALYs) in 2010. However, major depressive disorder also contributes to mortality for a number of other conditions. When the researchers added DALYs attributable to major depressive disorder for two of them, namely suicide and ischaemic heart disease, major depressive disorder ranked as the eighth leading cause of global burden.
Their results, the researchers say “not only highlight the fact that depressive disorders are a global health priority but also that it is important to understand variations in burden by disorder, country, region, age, sex, and year when setting global health objectives.”