Global health burden of illicit drugs and mental disorders on the rise

Dependence on opioids, including heroin, causes the greatest health burden (overall death and illness) of all the illicit drugs. Eric Constantineau

The global burden of death and illness attributable to mental disorders and illicit drug abuse has risen steadily in the last 20 years, two new studies have shown, but experts say policy is not keeping pace with the problems.

The two new studies, led by Australian researchers and published in the journal The Lancet today, are based on data drawn from the 2010 Global Burden of Disease study, the largest ever analysis of the global distribution and causes of major diseases, injuries, and health risk factors.

Mental health

The first study, titled “The Global Burden of Mental and Substance Use Disorders, 2010”, found that the burden of mental and substance use disorders increased by 37·6% between 1990 and 2010, driven mainly by changes in population growth and ageing.

That study also found that:

  • Mental and substance use disorders were the leading global cause of all non-fatal burden of disease.
  • Within the mental and substance use disorders group, depressive disorders accounted for 40·1% of disability adjusted life years (DALYs) – meaning the number of years lost due to ill-health, disability or early death – followed by anxiety disorders (14·5%), drug dependence (10·8%), and alcohol use disorders (9·5%). Eating disorders, childhood behavioural disorders, and pervasive developmental disorders together contributed 8·7% of DALYs accounted for by mental and substance use disorder.
  • The proportion of death and disease attributable to eating disorders was highest in Australasia.

Harvey Whiteford, Professor of Psychiatry and Population Health at the University of Queensland and lead author of this study, said that mental health had lagged behind other areas of medicine in terms of resources for treatment and research.

“We have a lot of catching up to do. There’s been a much bigger focus on mental health in recent years but we certainly don’t have a resource allocation commensurate with the size of the problem,” he said, adding that mental health disorders remain very stigmatised.

“People still present much later for treatment than we would like for good clinical outcomes.”

Ian Hickie, Professor of Psychiatry at the University of Sydney’s Brain and Mind Research Institute said the study “shows us that mental health and substance abuse are very, very large determinants of death and disability world wide.”

“Nowhere worldwide does the health system investment match the burden of disease. Even in Australia, where we are relatively advanced, we lag behind in health policy and service development,” said Professor Hickie, who was not involved in the study.

“In the lead up to the federal election, noone except The Greens is talking about mental health policy. The problem has not gone away and these are really serious, long term challenges,” Professor Hickie said.

Illicit drug use and dependence

The second study, titled “Global burden of disease attributable to illicit drug use and dependence: findings from the Global Burden of Disease Study 2010” found that the global burden of illness due to amphetamine, cannabis, cocaine, and opioids (including heroin) increased by 52% between 1990 and 2010.

The study also found that:

  • Opioid dependence caused the greatest burden of death and illness of the four drug categories studies.
  • Opioid and amphetamine dependence were the two most common forms of illicit drug dependence worldwide
  • Most individuals dependent on drugs were male (64% each for cannabis and amphetamines and 70% each for opioids and cocaine).
  • Cannabis use made a very small contribution to disease burden through its contribution as a risk factor for schizophrenia.
  • Suicide was another significant contributor to illicit drug burden because it is a common cause of death in regular users of opioids, cocaine, or amphetamines.
  • The overall burden of the four drugs studied is still less than that of smoking and alcohol, which are together responsible for around 10% of the total death and illness burden worldwide. The new study estimates that illicit drug dependence contributes to just under 1% of the total global burden of death and illness.

Louisa Degenhardt, Professor of Epidemiology, National Drug and Alcohol Research Centre at the University of New South Wales and lead author of the illicit drug study, said more resourcing was needed for drug interventions shown to work, such as methadone programs.

“The treatment of illicit drug use has fallen off the political agenda. The results here show that would be a mistake,” she said.

Alex Wodak, Emeritus Consultant at St Vincent’s Hospital, Darlinghurst said that “without the adoption of harm minimisation as Australia’s national official drug policy in 1985, the costs of drug use in this country would have been even greater than they have been.”

“As it is, Australia only allocates 2% of government drug expenditure to harm reduction compared to 66% to law enforcement,” said Dr Wodak, who was not involved in the study.

“This paper shows the cost of the dogged retention of the failed policy of drug prohibition.”

Although, as the authors noted, cannabis is the most widely used illicit drug in the world, it was responsible for no deaths, a lower prevalence of drug dependence than any of the other three drug types and only 10% of the global burden of illness due to illicit drugs, said Dr Wodak.

However, lead author of the illicit drugs study, Professor Degenhardt, said there was a “need to continue to develop interventions to prevent the onset of cannabis and psychostimulant (amphetamines and cocaine) dependence, and find treatment interventions that may be delivered to scale at the population level.”

“At present, we have limited options for the treatment of these disorders, particularly those which are able to be rolled out in low resource settings, which is the case in many countries worldwide,” she said.