Mental and substance use disorders responsible for more death and illness worldwide

Mental and substance use disorders were the leading cause of non-fatal illness worldwide in 2010, according to a new analysis from the Global Burden of Disease Study, published in The Lancet.

The result comes from a new analysis of the global burden (overall illness and death) attributable to mental and substance use disorders in 2010. Furthermore, mental and substance use disorders were together responsible for more of the global burden of death and illness than HIV/AIDS and tuberculosis, diabetes, or transport injuries. Depressive disorders accounted for the largest proportion of this burden, around two fifths (40%).

A team of researchers in Australia and the US, led by Professor Harvey Whiteford, analysed data on the 20 mental and substance disorders included in GBD 2010 to model the prevalence, premature death, and non-fatal illness caused by these disorders in 187 countries.

The researchers found that mental and substance use disorders were the fifth leading contributor to death and disease worldwide. When the researchers analysed the contribution of mental and substance disorders to non-fatal illness only, they found that they were responsible for more than a fifth (22.8%) of all disease burden, the leading cause worldwide.

This disparity is accounted for by the fact that mental and substance use disorders were recorded as having caused comparatively few deaths (232 000) in 2010, relative to the overall illness they caused. Most of the deaths recorded were attributable to substance use disorders. However, the authors point out that there is considerable premature mortality in people with mental disorders, but in GBD, their deaths are coded to the physical cause of death. Following GBD protocol, deaths by suicide are coded under injuries, even though most suicide is a result of mental disorder. In addition, deaths from illicit drugs are often recorded as accidental poisonings – and although the study modelling accounted for this where possible, the true number of deaths caused by illicit drug use  may be even higher.

From the 10 – 14 year age group onwards, girls and women had a greater burden of death and disease from mental disorders than did boys and men, whereas men had a greater burden from drug and alcohol dependence in all age groups.

The overall findings mask striking differences between world regions for some of the disorders analysed, with eating disorders showing the greatest overall variation; the proportion of death and disease attributable to eating disorders was nearly 40 times higher in Australasia, where prevalence was highest, than in western sub-Saharan Africa, where it was lowest. Only China, North Korea, Japan, and Nigeria had burdens of death and disease from mental and substance disorders which were statistically lower than the global average.

A substantially increased availability of data on the prevalence and effects of mental and substance disorders, as well as methodological improvements, meant that the analysis was able to account for considerably more disorders than the original Global Burden of Disease study in 1990, although data from some world regions (notably sub-Saharan Africa, parts of Asia, and central and eastern Europe) were scarce, resulting in greater statistical uncertainty over the estimates for these regions.

According to Professor Whiteford, “Mental and substance use disorders are major contributors to the global burden of disease and their contribution is rising, especially in developing countries. Cost-effective interventions are available for most disorders but adequate financial and human resources are needed to deliver these interventions.”  

“Despite the personal and economic costs, treatment rates for people with mental and substance use disorders are low, and even in developed countries, treatment is typically provided many years after the disorder begins.  In all countries, stigma about mental and substance use disorders constrain the use of available resources as do inefficiencies in the distribution of funding and interventions.  If the burden of mental and substance use disorders is to be reduced, mental health policy and services research will need to identify more effective ways to provide sustainable mental health services, especially in resource constrained environments.”