Mental health problems and substance abuse are causing more sickness and death worldwide than many chronic illnesses, a new study has found.

Mental disorders and the effects of substance abuse are the main cause of non-fatal illness worldwide, according to the research.

Researchers found that mental and substance disorders were responsible for more than a fifth (22.8%) of all the disease burden worldwide.

The study also found that mental and substance use disorders were together responsible for a greater proportion of the global burden of death and illness than HIV/ AIDS and TB, diabetes, or road traffic injuries.

The new analysis from the Global Burden of Disease Study, carried out by researchers from Australia and the US, was published in the Lancet.