Depression Now World's Second Leading Cause of Disability

Megan Brooks

November 06, 2013

Major depressive disorder (MDD) is the second leading cause of disability worldwide and a major contributor to the burden of suicide and ischemic heart disease, new data indicate.

The findings highlight the importance of including depressive disorders as a global health priority, researchers say.

The findings, published online November 5 in PLoS Medicine, stem from the latest Global Burden of Disease (GBD) study.

The 1990 GBD study ranked depression as the fourth leading cause of disease burden worldwide after lower respiratory infections, diarrheal diseases, and conditions arising during the perinatal period.

In the 2000 GBD study, depressive disorders were the third leading cause of disease burden behind lower respiratory infections and diarrheal diseases.

Depressive disorders now rank second in terms of global disability burden, according to the 2010 GBD study.

The study provides the most recent and comprehensive estimates the degree to which death and disability are attributable to depressive disorders, both worldwide and in individual countries and regions, the researchers say.

To arrive at the estimates, Alize Ferrari, from the University of Queensland and the Queensland Centre for Mental Health Research, in Australia, and colleagues compiled relevant data from all published research studies on MDD and the milder, chronic type of depression, dysthymia.

The researchers used disability-adjusted life years (DALYs) to quantify the global burden attributable to depressive disorders, calculated by adding years lived with a disability (YLDs) and years lost because of disease-specific premature death (YLLs).

When compared with other diseases and injuries, MDD accounted for 8.2% of global YLDs in 2010, making it the second leading cause of global disability and the eleventh leading cause of global burden (or DALYs) in 2010, the researchers report. Dysthymia accounted for 1.4% of global YLDs.

MDD and dysthymia were also leading causes of DALYs, accounting for 2.5% and 0.5% of global DALYs, respectively.

The burden of depressive disorders was higher in women than men; the largest proportion of YLDs from depressive disorders occurred among adults of working age.

The global burden of depressive disorders increased by 37.5% between 1990 and 2010 because of population growth and aging.

The investigators say that MDD accounted for an additional 16 million DALYs and 4 million DALYs when it was considered as a risk factor for suicide and ischemic heart disease, respectively. This "attributable" burden increased the overall burden of depressive disorders to 3.8% of global DALYs, they report.

The 2010 GBD study confirms that depressive disorders are a "leading direct cause of the global disease burden and show that MDD also contributes to the burden allocated to suicide and ischemic heart disease," the investigators say.

The findings "reinforce the importance of treating depressive disorders as a public-health priority and of implementing cost-effective interventions to reduce their ubiquitous burden,” they conclude.

As reported by Medscape Medical News, prior data from the GBD 2010 study found that mental and substance use disorders are the leading causes of nonfatal illness worldwide, with a global disease burden that trumps that of HIV/AIDS, tuberculosis, diabetes, and transport injuries.

The authors report no relevant financial relationships.

PLoS Med. Published online November 5, 2013. Full article


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