the developing world.

In China, only six percent of people coping with common mental illnesses such as depression or anxiety disorders or with substance abuse and dementia seek out a doctor, earlier research has shown.

Less than one percent of national healthcare budgets in China and India is allocated to mental health.

The global population afflicted with Alzheimer's or Parkinson's disease stood at 2.6 million worldwide in 2016, a more than 40 percent surge from only a decade earlier.

Alcohol and drug use accounted for some 320,000 deaths, including 86,000 for opioids. Opioid abuse -- mostly pharmaceutical -- in the United States has reached epidemic proportions.

"We are facing a triad of trouble holding back many nations and communities -- obesity, conflict and mental illness, including substance abuse disorders," said Christopher Murray, directorof the Institute for Health Metrics and Evaluation at the University of Washington in Seattle, which centralised and analysed the millions of data points used the studies.

Deaths attributed to conflict and terrorism -- notably in North Africa and the Middle East -- exceeded 150,000 in 2016, a jump of 140 percent compared to a decade earlier.

One bright spot was the better-than-expected health performance of several countries -- including Ethiopia, the Maldives, Nepal, Niger, Portugal and Peru -- that made outsized improvements in relation to national wealth, or GDP.

"These exemplar countries may provide information on successful policies that have helped to accelerate progress on health," said Murray.

In several cases, that headway stemmed in part from the rollout of antiretroviral treatments for HIV/AIDS.