Is the global burden of mental and substance use disorders increasing? Lancet.Nov.2013

20.11.2013

Global attention to disease associated morbidity is relatively new .Until 1990s  focus was on mortality with communicable diseases, cancer and cardiovascular disorders topping the priority. The first Global Burden of Disease study in 1990 (GBD 1990), showed that neuropsychiatric disorders ( neurological disorders, dementia, mental and substance use disorders) accounted for more than a quarter of all non-fatal burden,measured in years lived with disability .Five of the ten top disabling conditions were from this group. Depression was the most disabling disorder and the 4th on the list of overall disease burden.

In 2007 the new GBD (2010)  was launched which comprehensively reanalysed the  burden for 291 causes, 20 age groups, both sexes, and 187 countries in 21 world regions. For mental disorders, data were available for 85 countries in 19 world regions.  Disease categories were expanded to include more disorders. It used all community representative studies that used diagnostic techniques that could be mapped to DSM or ICD criteria published since 1980.Disability was weighted by survey methods were participants were asked to nominate the disorder phrase they deemed healthier than the comparator. Data from selected national surveys were used to derive severity distributions for every disorder.Premature mortality attributable directly to mental and substance use disorders ( Years of Life Lost) was calculated from causes of death estimates from 1980 to 2010.

Harvey A Whiteford et al summarise fatal, non-fatal, and total burden for eleven classes of mental and substance use disorders for 2010 with reference to changes in burden since 1990.

Results:

Disability Adjusted Life Years (DALY) : This  is Years of Life Lost (YLL) plus   Years Lived in Disability (YLD).Mental and substance use disorders accounted for  7·4% (6·2–8·6) of total disease burden in 2010 making it the fifth leading disorder category of global DALYs. In 1990 this was  only 5.4%.for mental disorders this is largely due to population growth and changing age structure.The prevalence of alcohol, opioid, and cocaine dependence increased notably between 1990 and 2010, whereas the prevalence of most mental disorders did not.With in this category, depressive disorders accounted for most DALYs (40%), followed by anxiety disorders, drug use disorders, and alcohol use disorders. The highest proportion of DALYs occurred in adolescents and young to middle-aged adults .

Years Lived in Disability (YLD): Mental and substance use disorders were the leading global cause of all non-fatal burden of disease taking 23%  of all non-fatal burden . 

Years of Life Lost (YLL ): In 2010 mental and substance use disorders were directly responsible for 8·6 million , equivalent to 232000 deaths. This is 0.5% of the total YLL.80% of these deaths were attributable to substance use disorders.

Limitations:

In most regions, data were available for prevalence, but not for other parameters. More studies were from  western Europe, North America, and Australasia .There were fewer studies related to low prevalence disorders (such as schizophrenia, bipolar disorder, and eating disorders)  and disorders with onset in childhood.Harmful use of alcohol and illicit drugs (defined in DSM as abuse) were not included in GBD 2010, which led to an underestimation of burden for substance use disorders.

The economic loss of this burden is huge. It is estimated that  the cumulative effect in the next 20 years  would be equivalent to 25% of global GDP in 2010.Treatment gaps are huge in developing countries.Scarcity of resources, inequities in their distribution, and inefficiencies in their use are complicated by stigma. Interventions at policy level can change this. Primary care interventions for depression could reduce the present burden of depression between 10% and 30%.

Conclusion: Total burden due to mental disorders and substance use disorders have increased by  by 37·6% between 1990 and 2010.They are the leading cause for years lived in disability.  

Summary of the article:

Global burden of disease attributable to mental and substance use disordersfindings from the Global Burden ofDisease Study 2010.

Whiteford HA, Degenhardt L, Rehm J, Baxter AJ, Ferrari AJ, Erskine HE, Charlson FJ, Norman RE, Flaxman AD, Johns N, Burstein R, Murray CJ, Vos T. Lancet. 2013 Nov 9;382(9904):1575-86.

  

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