Mental Illness in Global Health: Top Causes of DALYs

Mental illness is not just a personal struggle – it is one of the most significant contributors to disability and lost health across the globe. To measure this impact, researchers and health organizations use a metric called disability-adjusted life years (DALYs), which combines years of healthy life lost due to disability with years lost to premature death. The picture that emerges from this data is striking: mental disorders account for a growing share of the world’s total disease burden, and specific conditions – depression, alcohol use disorders, and schizophrenia – are responsible for a disproportionate amount of that toll. Understanding which conditions drive this burden, and who is most affected, is essential for shaping public health priorities worldwide.

What are DALYs and why do they matter?
Top contributors to DALYs from mental illness
Depressive disorders
Alcohol use disorders
Schizophrenia
Gender and age disparities in the burden of mental illness
Why women bear a heavier burden from depressive disorders
Why men bear a heavier burden from substance use disorders
Age patterns across the lifespan
Projections for 2030: depression set to dominate
Why this matters for global health policy

What are DALYs and why do they matter?

Before diving into the data, it helps to understand what DALYs actually measure. A single DALY represents one year of healthy life lost – either through living with a disabling condition or through dying prematurely. A disease that causes significant long-term disability but doesn’t directly kill people can still accumulate millions of DALYs globally. This is why mental disorders, which rarely appear as a direct cause of death on a death certificate, are so devastating from a public health standpoint: they are primarily conditions of disability, not mortality.

According to The Lancet Psychiatry’s Global Burden of Disease 2019 analysis, mental disorders were the second leading cause of years lived with disability (YLDs) worldwide, both in 1990 and again in 2019. The total DALYs attributable to mental disorders rose from 80.8 million in 1990 to 125.3 million in 2019 – a significant increase driven largely by population growth and aging. Mental disorders collectively grew from 3.1% to 4.9% of all global DALYs over that same period, with no signs of the burden reducing despite decades of research and intervention.

Top contributors to DALYs from mental illness

Not all mental disorders contribute equally to the global burden. A handful of conditions are responsible for the vast majority of DALYs, and each affects populations in distinct ways.

Depressive disorders

Depression dominates the rankings. Depressive disorders account for 37.3% of all mental disorder DALYs, making them by far the leading contributor within this category. At the disorder level, depressive disorders ranked second among all causes of years lived with disability globally, sitting just behind lower back pain. The World Health Organization estimates that around 5.7% of adults globally suffer from depression, and in high-income countries, only about one-third receive adequate treatment. Depression also functions as a risk multiplier – it raises the likelihood of suicide, worsens chronic physical conditions, and severely limits daily functioning over extended periods.

Alcohol use disorders

Alcohol use disorders (AUDs) represent the most prevalent form of all substance use disorders globally. In 2016 alone, alcohol-attributable causes were linked to an estimated 131.4 million DALYs worldwide, accounting for approximately 5% of all global DALYs. Unlike depression, which accumulates its burden through disability over time, alcohol use disorders drive DALYs through a combination of disability and premature death – through accidents, liver disease, cardiovascular complications, and violence. Alcohol use has consistently been ranked among the top ten major risk factors for disease burden in every global comparative risk assessment.

Schizophrenia

Schizophrenia affects a smaller share of the population than depression or anxiety, but its burden per person is extraordinarily high. The disability weight assigned to an acute psychotic episode is among the highest estimated across the entire Global Burden of Disease study – meaning that schizophrenia, when active, is among the most debilitating conditions a person can experience. It accounts for 12.2% of mental disorder DALYs, ranking third after depressive and anxiety disorders. The condition typically emerges in late adolescence or early adulthood, which means it strips away decades of productive, healthy life.

Gender and age disparities in the burden of mental illness

The global burden of mental illness is not distributed equally between men and women. Consistent patterns of disparity have been documented across large datasets, and they reflect a mix of biological differences, social stressors, and cultural norms around help-seeking and substance use.

Why women bear a heavier burden from depressive disorders

Women are significantly more likely than men to develop depression and anxiety disorders. Age-standardized DALY rates for mental disorders are notably higher among women (1,703.3 per 100,000) compared to men (1,426.5 per 100,000). The WHO confirms that women are more likely to have depression than men, with elevated risk linked to hormonal changes across the life course – including during puberty, the postpartum period, and menopause – as well as higher rates of exposure to trauma, intimate partner violence, and caregiving burdens. Among young people aged 15-24, girls and young women show substantially higher age-standardized rates for both anxiety and depressive disorders compared to their male peers, a pattern that continues into adulthood.

The WHO’s 2025 World Mental Health report confirms that while the prevalence of mental health disorders can vary by sex, women are disproportionately impacted overall – particularly by anxiety and depressive disorders. Social determinants play a substantial role: gender inequality, economic dependence, and limited autonomy in many regions create conditions that are strongly associated with depression onset and persistence.

Why men bear a heavier burden from substance use disorders

The pattern almost reverses when it comes to substance use. The alcohol-attributable burden of disease is significantly higher among men than women, a disparity seen across nearly every country and region. High alcohol use is the second highest risk factor for DALYs among men aged 15-49, but only the 14th highest risk factor among women in the same age group – a stark contrast that highlights how differently this risk is distributed.

Men are more likely than women to engage in illicit drug use and to begin using alcohol or drugs at a younger age, contributing to a rate of substance dependence that is roughly twice as high as women’s. Research into the underlying reasons points to several factors: delayed maturation of the prefrontal cortex in adolescent males, testosterone-mediated changes in dopamine reward pathways that heighten sensitivity to addictive behaviors, and cultural norms that normalize or even celebrate male risk-taking and heavy drinking. These biological and social dynamics together create a pattern where men shoulder a disproportionate substance-use burden, while women carry more of the depression burden.

Age patterns across the lifespan

DALYs for mental and substance use disorders peak in early adulthood, which is particularly significant because it means these conditions rob individuals of healthy years during what should be their most productive and socially engaged phase of life. DALYs increase through childhood and peak around age 35, then gradually decline with age. Schizophrenia and bipolar disorder tend to emerge in late adolescence and early adulthood, while depression spans all adult age groups and carries an especially heavy burden in older populations, particularly older women.

Projections for 2030: depression set to dominate

Current data already shows the scale of mental illness as a global health issue. The projections for 2030 suggest the situation is going to become more urgent.

According to the WHO Eastern Mediterranean Regional Office, depression is already among the ten leading causes of DALYs globally and is projected to be among the top three causes of DALYs lost by 2030. More broadly, major depression alone is expected to be the largest single contributor to the global disease burden by 2030, outpacing cardiovascular disease, cancer, and respiratory conditions in terms of total DALYs.

A 2024 study published in the Journal of Affective Disorders used Bayesian modeling to project depression trends through 2030, and found that the burden of depressive illness is expected to be substantially higher in women, with projected age-standardized incidence rates of 3,835 per 100,000 women compared to 2,519 per 100,000 men. Critically, even if age-standardized rates stabilize, the absolute number of people affected will continue to climb as populations grow and age. The WHO estimates that depression accounts for 4.3% of the global disease burden and will rank as the leading contributor by 2030 due to premature deaths and years lived with disability.

WHO projections suggest that by 2030, the disability and life lost from depression will exceed that from war, accidents, cancer, stroke, and heart disease combined – a projection that underscores just how consequential the under-treatment of depression has become. A WHO-led study found that low levels of recognition and access to care for depression and anxiety already result in a global economic loss of one trillion US dollars every year, a figure that will only grow if current trends continue. For every dollar invested in scaling up depression and anxiety treatment, the return in health and productivity gains is estimated at four dollars.

Why this matters for global health policy

The data on DALYs from mental illness makes one thing clear: mental health is not a niche public health issue. It is a central driver of the global disease burden, and it is getting larger. The GBD 2021 study highlights a continued and worsening global burden of mental disorders, further intensified by the COVID-19 crisis, which drove sharp increases in depression and anxiety cases through mechanisms including social isolation, economic stress, and direct neurological effects of SARS-CoV-2 infection.

Despite this evidence, mental health conditions represent the second biggest reason for long-term disability globally, yet funding, trained providers, and accessible services remain dramatically insufficient. The gap between need and available care is widest in low- and middle-income countries, where the vast majority of the one billion people living with mental disorders reside, and where the projected growth in burden is also highest.

Reducing the DALY burden from mental illness will require gender-responsive strategies – different approaches are needed to address depression in women and substance use in men – alongside major investments in mental health infrastructure, early intervention, and stigma reduction globally.

What do you think? Given that depression is projected to become the top cause of global disability by 2030, what factors do you think explain why mental health systems in most countries are still so underfunded relative to this scale of burden? And considering the clear gender disparities – women more affected by depression, men more by substance use disorders – should mental health policies be designed differently for men and women?

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Table of Contents

What are DALYs and why do they matter? 🔗

Top contributors to DALYs from mental illness 🔗

Depressive disorders 🔗

Alcohol use disorders 🔗

Schizophrenia 🔗

Gender and age disparities in the burden of mental illness 🔗

Why women bear a heavier burden from depressive disorders 🔗

Why men bear a heavier burden from substance use disorders 🔗

Age patterns across the lifespan 🔗

Projections for 2030: depression set to dominate 🔗

Why this matters for global health policy 🔗