Global burden of mental disorders and illicit drug use – experts respond

Mental health and substance abuse 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 today. 

A team of researchers in Australia and the US analysed data from 20 mental and substance disorders to model the prevalence, premature death, and non-fatal illness caused by these disorders in 187 countries.

Among the findings:

  • High income countries have the highest burden of disease due to drug use
  • Women and girls were more affected by mental disorders while men and boys were more affected by drug and alcohol abuse
  • Opioids (such as morphine, heroin and codeine) caused the greatest burden of disease, and Australasia has the highest rates of opioid dependence in the world

While mental health and substance use disorders were not ranked highly as a direct cause of death, they were responsible for the greatest number of years lived with disability. They were the cause of 175 million person-years lived with disability in 2010.

A second analysis, also published in the Lancet, focused specifically on illicit drug use disorders.

The results show that the burden in the worst affected countries (largely high-income nations such as USA, UK, New Zealand and Australia) was 20 times greater than in the least affected countries.

In terms of health loss due to substance use disorders, New Zealand was ranked 16th out of the 187 countries examined (see appendix table A4) however the wide range of uncertainty in the modelling analysis and the possibility of some countries under-reporting data, mean this ranking is approximate.

According to the study, for every 100,000 people in NZ, approximately 640 years of good health was lost through disease, suicide and mental disorders due to illicit drug use disorders in 2010.

A full media release from the Lancet is available here, and an inforgraphic video, detailing the findings, can be viewed here.

The SMC collected the following expert commentary. Feel free to use these quotes in your reporting. If you would like to contact a New Zealand expert, please contact the SMC (04 499 5476;

Associate Professor Nick Wilson is co-director of the Burden of Disease Epidemiology, Equity and Cost-Effectiveness Programme, University of Otago, Wellington and contributor to the Public Health Expert blog. He comments:

“These two studies published in the Lancet are a valuable contribution to knowledge about health problems and they come from a massive international research project. The results should help guide policy makers around the world in taking the cost-effective steps needed to prevent and treat the high health burden from mental and substance use disorders.

“Actually from the New Zealand perspective, these international findings are largely compatible with those from New Zealand’s own national study on health loss. This Ministry of Health work was only just released a few weeks ago. It shared key definitions and methods with the Lancet studies, but the New Zealand work had access to more local data.

“The Ministry’s study also found that “anxiety and depressive disorders” were very important. Indeed, these were the second most important cause of health loss after coronary heart disease (but for NZ women they were the first cause of health loss, ahead of heart disease). The New Zealand study also reported that amongst youth (aged 15-24 years), alcohol use disorders were the leading cause of health loss (14% of the total for this age-group), followed closely by anxiety and depressive disorders.

“The Lancet paper on mental health and substance use reported that “cost-effective interventions are available for most disorders”. Indeed, some responses would actually be cost-saving to the government and to society – eg, higher alcohol taxes. Increasing alcohol taxes are well proven to reduce alcohol-related health harm – and would probably also reduce social damage from alcohol-related crime and violence. There is also evidence from a systematic review that there are other cost-effective alcohol controls eg, marketing restrictions.

“Although alcohol is bigger problem than illicit drugs (several times bigger for New Zealand) – illicit drugs still cause significant health loss internationally, including from suicide, fatal overdose and infections from drug injecting (eg, hepatitis C). New Zealand was a world leader in harm reduction from illicit drug use by adopting a needle and syringe exchange programme in the 1980s, at an early stage of the HIV/AIDS pandemic. As with many other developed countries, it also provides methadone programmes to reduce both health and social harm from drug use. Most recently, New Zealand has been innovative with a new law involving a pre-market approval scheme with testing requirements and retail restrictions for psychoactive substances that are considered to be “low-risk”.

“From a health economics perspective there is evidence from an international review  that needle-syringe exchange programmes are cost-effective. In Canada a supervised injection facility has been reported to be cost saving. There is also evidence from a systematic review  that both buprenorphine maintenance therapy and methadone maintenance therapy are cost-effective for the management of opioid-dependent individuals.

“In summary, this international work, alongside the recent New Zealand work, should encourage responses by governments and health workers to do more to prevent and treat the high health burden from mental and substance use disorders – it would appear to be a cost effective area to achieve health gains. In particular, they should take the potentially cost saving steps first, such as raising alcohol tax.”

Additional note on methods:

“Why did the Lancet studies and the NZ study use disability-adjusted life years (DALYs) to measure health loss? This metric is a useful way to allow health loss from premature death (lost years of life) to be combined with health loss from illness (loss of healthy life). This allows comparisons between the spectrum of different health outcomes. For example, between those conditions that don’t cause death (eg, mild anxiety), with those that cause both death and suffering (eg, depression causes both chronic suffering and suicide), and with those where the health burden is largely from premature death (eg, lung cancer).”

Read more on Prof Wilson’s blog Public Health Expert.