One in two people will suffer a mental health disorder by the age of 75, according to a Queensland University report.

Report author Professor John McGrath said the most common disorders were major depression and anxiety.

He said the study, done in conjunction with Harvard medical school, incorporated data from face-to-face interviews with more than 150,000 adults across 29 countries over a 21-year period.

McGrath said the most common mental health issues among men were alcohol abuse, depression, and a specific phobia.

For women, specific phobias and depression were most common, as was post-traumatic stress disorder.

He said the research showed that most mental health disorders first became apparent in 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,” he said.

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

The researchers urged governments to priorities mental health services for young people.