A global study co-led by researchers from The University of Queensland and Harvard Medical School has found one in two people will develop a mental health disorder in their lifetime.

Professor John McGrath from UQ's Queensland Brain Institute, Professor Ronald Kessler from Harvard Medical School, and their colleagues from 27 other countries, analyzed data from more than 150,000 adults across 29 countries between 2001 and 2022, taken from the largest ever coordinated series of face-to-face interviews—the World Health Organization's World Mental Health Survey initiative.

Lead author Professor McGrath said the results demonstrate the high prevalence of mental health disorders, with 50 per cent of the population developing at least one disorder by the age of 75.

"The most common were mood disorders such as major depression or anxiety," Professor McGrath said.

"We also found the risk of certain mental disorders differed by sex."

The three most common mental health disorders among women:

• Depression
• Specific phobia (a disabling anxiety that interferes with daily life)
• Post-traumatic stress (PTSD)

The three most common mental health disorders among men:

• Alcohol abuse
• Depression
• Specific phobia

The research also found mental health disorders typically first emerge in childhood, adolescence or young adulthood.

"The peak age of first onset was at 15 years old, with a median age of onset of 19 for men and 20 for women," Professor McGrath said.

"This lends weight to the need to invest in basic neuroscience to understand why these disorders develop."

Professor Kessler said investment was also needed in mental health services with a particular focus on young people.

"Services need to be able to detect and treat common mental disorders promptly, and be optimized to suit patients in these critical parts of their lives," Professor Kessler said.

"By understanding the age at which these disorders commonly arise, we can tailor public health interventions and allocate resources to ensure that appropriate and timely support is available to individuals at risk."

The researchers said the outcomes provide valuable insights into the frequency and timing of mental disorder onset based on many different populations.

The study is published in The Lancet Psychiatry.