Over half the world's population will have a mental disorder by age 75: study

A cross-national analysis recently published in The Lancet Psychiatry has found that if current trends persist, over half the world's population will develop a mental illness by the age of 75.

Researchers analyzed data from over 150,000 respondents who participated in 32 WHO Composite International Diagnostic Interview surveys across 29 countries from all corners of the globe between 2001 and 2022. 

They found that the overall lifetime prevalence of any mental disorder was 28.6 percent for males and 29.8 percent for females, with the latter 9 percent more likely, 54.5 versus 45.4 percent, to be at morbid risk by age 75. The median age of onset for men and women was 19 and 20, respectively. 

While the condition most likely to be experienced by both sexes was major depressive disorder, alcohol use disorder was most prevalent in men, and specific phobias were seen most in women.

Other illnesses discussed in the study include panic disorder, generalized anxiety, post-traumatic stress disorder, bipolar disorder, alcohol dependence, substance abuse, attention deficit hyperactivity disorder, and explosive anger. Women were found to be more likely to suffer from all of the above, save for the last four.

Among those who took part in the massive meta-analysis was Professor Ronald Kessler, Harvard Medical School's McNeil Family Professor of Health Care Policy. He drew attention to the fact that many of such disorders "typically first emerge in childhood, adolescence, or young adulthood," suggesting that risk later on in life could be mitigated by seeking treatment as early as possible.

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

Fellow researcher and professor John McGrath went on to suggest that the finding "lends weight to the need to invest in basic neuroscience to understand why these disorders develop, as well as mental health services that have a particular focus on young people."