Mental disorders now affect nearly 1.2 billion people worldwide, with anxiety and depression driving a sharp rise since 1990.
Mental disorders are now affecting almost 1.2 billion people worldwide, after global case numbers nearly doubled since 1990, according to new research.
The sharp rise over the past three decades means mental health disorders now account for more than 17 per cent of all disability worldwide, a report published this week has found.
The peer-reviewed study, conducted by researchers at the Institute for Health Metrics and Evaluation and the University of Queensland, was published in the medical journal The Lancet.
In 1990, there were an estimated 599 million cases of mental health disorders across the globe.
By 2023, that figure had climbed to an estimated 1.17 billion cases worldwide.
Among the 12 mental disorders examined, anxiety disorders and major depressive disorders were found to be the most common.
Cases of anxiety disorders rose from 182 million in 1990 to 470 million in 2023, marking an increase of more than 47 per cent after adjusting for population growth.
Major depressive disorders also increased by 24 per cent, rising from 102 million cases in 1990 to 236 million cases in 2023.
The report’s lead author, Dr Damian Santomauro, is an associate professor at the Queensland Centre for Mental Health Research and an affiliate assistant professor at IHME.
“Addressing this growing challenge will require sustained investment in mental health systems, expanded access to care, and coordinated global action to better support populations most at risk,” he said.
The report examined available data for 12 different mental disorders, including anxiety disorders, schizophrenia, bipolar disorder, anorexia and bulimia.
The data was taken from IHME’s 2023 Global Burden of Disease study, described as the largest and most comprehensive health study to date.
The study was first carried out in 1990.
By comparing case numbers, researchers were also able to calculate “disability-adjusted life-years”, known as DALYs.
Mental disorders became the fifth leading cause of DALYs globally in 2023, rising sharply from 12th place in 1990.
In total, mental disorders accounted for 171 million lost years of life globally in 2023.
“Declining mortality rates from communicable, maternal, nutritional and neonatal diseases over the past 30 years have allowed many more individuals to live longer,” the report said.
“But [that is] not without increasing occurrences of chronic and disabling illnesses such as mental disorders.
“However, [Global Burden of Disease study] 2023 findings suggest that we are entering an even more concerning phase of worsening mental disorder burden globally.”
The report also found that both case numbers and DALYs were not distributed equally across the world.
Anxiety disorders and major depressive disorders made up the largest share of the mental disorder burden.
Both disorders were also among the 20 leading causes of DALYs in 152 of the 204 countries included in the Global Burden of Disease study.
Both conditions peaked in the years following the COVID-19 pandemic.
Although schizophrenia had lower case numbers, it was the third-leading cause of mental disorder DALYs globally “due to its high severity”.
The report found that people were affected at every stage of life, although the type of mental health disorder varied according to age.
Co-author Dr Alize Ferrari is an honorary associate professor at the Queensland Centre for Mental Health Research, in partnership with the University of Queensland, and an affiliate assistant professor at IHME.
“Our findings show that mental disorder burden peaks among 15–19-year-olds, which is a critical development period that can shape trajectories for education, employment, and relationships,” she said.
All 12 disorders reviewed were present among the 15–19 age group, which the report identified as the age at which anxiety disorders and major depressive disorder became most prevalent.
The DALY rate remained high between the ages of 20 and 39, before gradually declining from age 40 onwards.
“Overall, these trends highlight the need to promote mental wellbeing across the life course, with prevention and early intervention to improve outcomes for children, families, and communities into adulthood,” the report said.
Women were also disproportionately affected, with 620 million females globally living with a mental disorder in 2023.
That compared with 552 million males of all ages living with a mental disorder during the same period.
Women also carried a higher overall mental illness burden, totalling 92.6 million DALYs, compared with 78.6 million among men.
“Compared with males, females experience lower self-esteem, greater tendency towards body-related shame, and higher rates of domestic violence and sexual abuse,” the report said.
The report said further research was needed to examine the factors contributing to the difference between men and women.
Professor Philip Batterham, co-head of the Australian National University’s Centre for Mental Health Research, said the results were “not surprising”.
However, he urged caution when interpreting estimates of mental disorder rates.
“It has gone up markedly, but so has the population over that period from 1990 to 2023,” he told the ABC.
“If you’re looking at the age-standardised rates, that’s a better indicator of how much it’s going up in terms of proportions.”
The report noted that it had attempted to reduce errors caused by different case definitions and data collection methods, an issue Dr Batterham also identified as a possible limitation.
“They’re typically using self-report measures,” Dr Batterham said.
“So people would report what symptoms they’re experiencing and then from that we can infer whether they might meet criteria for a mental disorder.
“But this isn’t the same as being diagnosed with a mental disorder, so in some cases you do get overestimates.”
He added that different cultural understandings of mental disorders could also affect case numbers.
“There are global trends towards greater inequity, greater globalisation that may lead to changes within different cultures and potentially increasing levels of mental ill health [in those regions],” he said.
“Because mental health is such a complex sort of health condition, it’s influenced by all sorts of factors.
“As we’ve seen more global changes such as war and economic challenges … things like technology use and changes to employment can also have impacts at an individual level.
“A range of factors there in terms of relationships, things like sleep habits, lifestyle habits can also impact on mental health.
“When you put all those together, there’s potential for these global drivers … as well as more local and individual factors that might influence these numbers we’re seeing.”
