The number of people with mental disorders worldwide has nearly doubled over the past three decades to approximately 1.2 billion, with mental illness now overtaking cancer and cardiovascular disease as the leading cause of disability globally, according to a new analysis.
A joint research team from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington School of Medicine and the University of Queensland in Australia announced Monday that they had published their findings in The Lancet, analyzing the prevalence and disease burden of mental disorders across 204 countries and territories worldwide from 1990 to 2023.
The team examined 12 mental disorders, including anxiety disorders, major depressive disorder (MDD), schizophrenia, bipolar disorder, autism spectrum disorder, and ADHD.
The analysis estimated that approximately 1.17 billion people worldwide had a mental disorder as of 2023, with 620 million women and 552 million men affected. This represents a 95.5% increase in patient numbers compared to 1990. Researchers attributed the rise to a combination of population aging, social changes, and the psychological impact following the COVID-19 pandemic.
Anxiety disorders and major depressive disorder drove much of the recent increase. The age-standardized prevalence of major depressive disorder rose 24% compared to 2019, while anxiety disorders surged 47% over the same period. Both conditions saw their increases accelerate during the COVID-19 pandemic.
"The rise in mental disorders may reflect not only pandemic-related stress but also long-term structural factors such as poverty, social instability, abuse and violence, and weakening social connections," said Damian Santomauro, professor at the University of Queensland, who led the research.
Mental disorders also ranked high in the global disease burden. Based on disability-adjusted life years (DALYs)—which combine years of healthy life lost to disease or disability with years lost to premature death—mental disorders ranked fifth among all causes of disease burden, the team said.
In terms of years lived with disability (YLDs), which measures time spent living with a disability, mental disorders accounted for 17.3% of the total. This was the highest globally, exceeding cardiovascular disease, cancer, and musculoskeletal disorders. The researchers concluded that mental illness goes beyond an individual issue and represents a societal problem affecting academic performance, labor market participation, personal relationships, and overall productivity.
By age group, the burden was greatest among adolescents. The DALY ratio peaked among those aged 15 to 19. The team noted that this period coincides with brain development and the formation of social identity, suggesting that mental disorders are likely to have long-term effects on academic achievement, interpersonal relationships, and adult mental health.
Disease types also varied by age. Autism spectrum disorder, ADHD, conduct disorder, and idiopathic intellectual disability were common in childhood, while anxiety and depressive disorders rose sharply from adolescence onward.
Women bore a heavier mental disorder burden than men. As of 2023, women's mental disorder DALYs stood at 2,239.6 per 100,000 population, significantly higher than men's 1,900.2. The team attributed this to a combination of factors including exposure to domestic and sexual violence, caregiving burdens, and structural inequalities.
By region, high-income countries such as those in Australasia and Western Europe showed high mental disorder burden rates. At the same time, increases were also pronounced in parts of sub-Saharan Africa and South Asia.
The treatment gap remained the central problem. Only 9% of patients with major depressive disorder received adequate treatment globally on average. In 90 countries, treatment access rates fell below 5%. By contrast, some high-income countries such as Australia, Canada, and the Netherlands posted treatment rates above 30%.
"Access to mental health services must be expanded in low- and middle-income countries, and policies focused on early treatment and prevention should be strengthened," the research team said. "Sustained investment in mental health systems and international cooperation are essential."
