A major international study has revealed that mental disorders are now the world’s leading cause of disability, affecting nearly 1.2 billion people globally in 2023.
Researchers say the findings show how rapidly mental health problems have increased over recent decades and warn that healthcare systems are struggling to keep up.
The study was conducted by researchers from the Institute for Health Metrics and Evaluation together with scientists from the University of Queensland. The results were published in The Lancet and represent one of the largest studies ever carried out on mental health worldwide.
The researchers analyzed data from 204 countries and territories between 1990 and 2023. They examined mental health conditions across 25 age groups, both sexes, and 21 world regions.
Mental disorders are illnesses that affect thinking, emotions, behavior, or mood. These conditions can interfere with work, relationships, learning, and daily life. Common disorders include anxiety, depression, autism spectrum disorder, ADHD, and conduct disorder.
The new study found that the global number of people living with mental disorders has almost doubled since 1990. Researchers say this increase reflects both population growth and a real rise in mental health problems.
In 2023, mental disorders caused 171 million disability-adjusted life years, often shortened to DALYs. This measure reflects years lost because of illness, disability, or early death.
Mental disorders now account for more than 17 percent of all years lived with disability worldwide. According to the researchers, this means mental illness now creates more disability globally than heart disease, cancer, or muscle and joint conditions.
Among the conditions studied, anxiety disorders and major depressive disorder contributed most strongly to the growing burden.
Since 2019, rates of major depressive disorder have increased by around 24 percent worldwide. Anxiety disorders increased by more than 47 percent during the same period.
Researchers believe the COVID-19 pandemic played an important role in worsening global mental health. During the pandemic, many people experienced isolation, financial difficulties, grief, stress, uncertainty, and major disruptions to daily routines.
However, the researchers also say broader long-term social problems are contributing to rising mental illness rates. These include poverty, violence, insecurity, abuse, discrimination, and weaker social connections between people.
Lead researcher Dr. Damian Santomauro from the Queensland Center for Mental Health Research explained that solving the problem will require long-term investment in mental health systems and greater global cooperation.
The study also revealed important differences between age groups.
Mental health burden was highest among teenagers aged 15 to 19 years. Researchers say this is especially concerning because adolescence is a critical stage of development. Mental health problems during these years can affect education, employment opportunities, friendships, relationships, and long-term life outcomes.
In younger children, conditions such as autism spectrum disorder, ADHD, conduct disorder, and developmental intellectual disability were more common. Boys were more likely than girls to experience these childhood developmental disorders.
As children entered adolescence, anxiety disorders and depression became the main contributors to mental health burden.
The researchers also found that women carry a greater overall mental health burden than men. In 2023, approximately 620 million women worldwide were living with mental disorders compared with 552 million men.
Women also experienced higher overall disability related to mental illness. Researchers say this may reflect several factors, including greater exposure to domestic violence, sexual abuse, caregiving stress, gender discrimination, and social inequality.
The burden of mental illness increased in every region of the world over the past three decades.
Some of the highest rates were found in wealthier regions such as Australasia and Western Europe. Countries including Australia, Portugal, and the Netherlands recorded particularly high burden rates.
Large increases were also seen in parts of South Asia and Western sub-Saharan Africa.
The study highlights not only the health impact of mental disorders but also the economic and social consequences. Mental illness affects families, workplaces, schools, and communities. It can reduce productivity, increase healthcare spending, and place heavy emotional pressure on caregivers.
One of the most troubling findings involved the lack of access to treatment.
The researchers estimated that only around 9 percent of people worldwide with major depressive disorder receive minimally adequate treatment. In many countries, treatment rates are far lower.
In 90 countries, fewer than 5 percent of people with depression receive adequate care. Only a small group of high-income countries provide adequate treatment to more than 30 percent of affected individuals.
The researchers say improving access to care is now urgently needed, especially in low-income and middle-income countries where mental health services are often severely underfunded.
Experts also believe reducing stigma around mental illness remains important. Many people avoid seeking help because they fear judgment, discrimination, or misunderstanding from others.
The findings suggest the world is facing a major mental health challenge that may continue growing if governments do not take stronger action. Researchers say more investment in prevention, early intervention, education, and mental healthcare services could help reduce the burden in future generations.
Although the study presents a worrying picture, the researchers hope the findings will encourage governments and healthcare systems to treat mental health with the same urgency as physical health.
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Source: University of Queensland.
