The world faces “an emerging crisis” of higher death rates among teenagers and young adults, according to a major study on the causes of death and disability worldwide.

The reasons vary from drug and alcohol use, and suicide in North America, to infectious diseases and injuries in sub-Saharan Africa, the researchers said, but warned that their data should serve as “a wake-up call”.

The study also found that chronic diseases such as heart disease and diabetes now accounted for two-thirds of all ill health and that mental health problems were surging.

Half of the world’s disease burden was preventable, researchers calculated, driven by risks that could be reduced, such as high blood pressure, air pollution, smoking and obesity.

The Global Burden of Disease study was carried out by a network of 16,500 scientists using more than 300,000 data sources. It is published in the Lancet and was presented at the World Health Summit in Berlin on Sunday.

It found that, as of 2023, death rates had fallen overall in all 204 countries and territories, and global life expectancy had recovered from a dip caused by the Covid-19 pandemic.