Half of World’s Population Will Experience a Mental Health Disorder

Large-scale study based on surveys in 29 nations sheds new light on major health problem

An older person holds a distressed younger person’s hands and shoulder, offering comfort.
Image: ChayTee/iStock/Getty Images Plus

At a glance:

  • One out of every two people in the world will develop a mental health disorder in their lifetime.
  • A massive, coordinated international collaboration conducted more than 150,000 face-to-face surveys across 29 countries of varying wealth around the world.
  • Insights from study can help public health workers, clinicians, and researchers better respond to unmet needs of people with mental health disorders.

One out of every two people in the world will develop a mental health disorder in their lifetime, according to a large-scale study co-led by researchers from Harvard Medical School and the University of Queensland. The findings are based on structured, face-to-face surveys of more than 150,000 adults across 29 countries of varying wealth from all of the regions of the world. The results are published in The Lancet Psychiatry.

Get more HMS news here

Massive burden of disease

The researchers said the results demonstrate the high prevalence of mental health disorders worldwide, with 50 percent of the population developing at least one disorder by the age of 75. The findings provide valuable insights into the frequency and timing of mental disorder onset across many different populations, the researchers said.

Ronald Kessler, the McNeil Family Professor of Health Care Policy in the Blavatnik Institute at HMS, John McGrath, conjoint professor at UQ’s Queensland Brain Institute, and their colleagues from 27 other countries analyzed data collected between 2001 and 2022 as part of the WHO’s World Mental Health Survey Initiative, which is based at HMS.