Introduction Mental health is a fundamental pillar of sustainable development. When left unaddressed, its impacts accumulate across the life course, weakening human capital and widening social and economic inequalities. Evidence consistently shows that investing in mental health delivers strong returns for both individuals and societies. Mental disorders represent one of the largest contributors to global disability. Although they account for a relatively small share of mortality, their impact on years lived with disability is substantial, making them a major challenge for both health systems and sustainable development. The World Health Organization (WHO) estimates that nearly one billion people were living with a mental disorder globally in 2019. WHO also reports that people with severe mental health conditions die on average 10–20 years earlier than the general population, mostly due to preventable physical diseases. Economic Impact Mental disorders impose a substantial economic burden that extends beyond health care expenditures. Globally, economic losses associated with mental disorders are estimated at approximately $5 trillion per year. Depression and anxiety disorders account for a significant share of these losses. Unlike many other diseases, the majority of the economic burden arises from indirect costs, which are about twice as high as direct costs. Poor mental health during working age can reduce productivity, limit job stability, and contribute to long-term financial insecurity. Mental disorders are closely linked to poverty. Individuals experiencing mental health conditions may face reduced income opportunities and increased health expenditures, while poverty itself can increase exposure to stress and other risk factors. This dynamic creates a cycle in which mental ill-health and economic hardship reinforce one another. Life Course Approach A life course approach to health emphasizes addressing health needs at every stage of life from a healthy start in early childhood, optimal development (of infants, children, adolescents and youth), adult health and well-being, healthy aging, and a dignified death at any age. This perspective is widely recognized as essential for achieving Sustainable Development Goal 3, which aims to ensure healthy lives and promote well-being for all. It also highlights the role of social determinants of health and health equity in shaping long-term outcomes. WHO’s framework to implement a life course approach in practice provides guidance on how to apply this lens to reorient health systems and redesign primary health care programs to improve health and well-being across generations. Childhood and adolescence This stage is characterized by rapid brain and psychosocial development. Mental health conditions affect about 1 in 12 children and 1 in 7 adolescents globally, with an estimated 148 million young people in Asia living with a mental disorder. These early challenges can disrupt learning, relationships, and future opportunities. One in three college students experience symptoms of depression, anxiety, suicidal ideation, or self-injury, which can affect academic performance and interpersonal relationships. Working age (adulthood) Mental health in adolescence carries forward into adulthood, influencing roughly one-quarter of adult mental health outcomes, as well as broader aspects of life including physical health, employment, and social participation. Aging Mental health increasingly intersects with chronic illness and social isolation. Of the 57 million people worldwide who require palliative care, two-thirds are over 50 and most live in low- and middle-income countries. Without timely support, these layered vulnerabilities deepen inequities and increase care needs across societies. Between 2011 and 2030, cumulative global economic output losses attributable to mental disorders are projected to reach $16.3 trillion, a burden comparable to cardiovascular diseases and exceeding that of several other major non-communicable diseases. Support for Mental Health Despite this burden, investment in mental health remains limited. Most Asian countries allocate only about 2% of health spending to mental health and treatment gaps can reach up to 90% in low-resource settings. Thus, strengthening mental health across health systems is essential for protecting human capital, reducing inequality, and supporting inclusive and sustainable development. Investing in mental health generates benefits that extend far beyond the health sector. Global analyses suggest that every $1 invested in treatment for depression and anxiety can generate about $4 in improved health and productivity outcomes. Furthermore, adolescent mental health interventions have been estimated to generate returns of approximately $23.6 for every $1 invested, demonstrating that investments earlier in life can yield even greater benefits. These gains accumulate across the life course. Strengthening primary healthcare is a key pathway to address these challenges by promoting community-based and preventive services, which remain underdeveloped, contributing to large treatment gaps. Most essential universal health coverage services can be delivered through primary healthcare, making it an effective platform for integrating mental health services across the life course. Embedding mental health within primary healthcare systems can expand access to care, improve early detection and treatment, and support continuous care from maternal and child health services to chronic disease management. In this context, the WHO Mental Health Gap Action Programme guideline supports non-specialist providers in delivering care for priority mental conditions, facilitating the integration of mental health into primary healthcare, and helping to close treatment gaps. Expanding community-based services and integrating mental health into primary healthcare systems can help close treatment gaps and ensure continuity of care, aligning with the Comprehensive Mental Health Action Plan 2013–2030. Conclusion Mental health enables people to cope, learn, work, and contribute to their communities. Addressing challenges can strengthen human capital and reduce inequality. Therefore, investing in mental health becomes both a health priority and a strategic investment in sustainable development and resilient societies. Note: This joint Insight piece derives from the Asian Development Bank (ADB) webinar on Investing in Mental Health and a background document to the Mental Health Psychosocial Support Simulation Workshop, which ADB is co-hosting with Thailand's Department of Mental Health, the World Health Organization, and the European Humanitarian Aid to be held on 22–25 June 2026 in Bangkok, Thailand. Resources A. Maddock et al. 2021. Psychological and Social Interventions for Mental Health Issues and Disorders in Southeast Asia: A Systematic Review. International Journal of Mental Health Systems. (15) 49. Asian Development Bank. 2024. Key Strategies to Improve Mental Health Support Across Asia and the Pacific. D. Arias, S. Saxena, and S. Verguet. 2022. Quantifying the Global Burden of Mental Disorders and Their Economic Value. eClinical Medicine. 54 (101675). J. Purtle and L. A. Roman. 2018. Mental Health Stigma and Communication and Their Intersections with Education. Communication Education. 67 (3). pp. 336–339. J. Zhang, Y. Liu, and X. Zhang. 2025. The Burden of Mental Disorders, Substance Use Disorders and Self-Harm Among Young People in Asia, 2019–2021: Findings from the Global Burden of Disease Study 2021. Psychiatry Research. World Health Organization. 2025. Framework to Implement a Life Course Approach in Practice. Ask the Experts Eduardo P. Banzon Director, Health Practice Team, Human and Social Development Office, Sectors Department 3, Asian Development Bank Dr. Eduardo Banzon champions Universal Health Coverage and has long provided technical support to countries in Asia and the Pacific in their pursuit of this goal. Before joining ADB in 2014, he was President and CEO of the Philippine Health Insurance Corporation, World Health Organization (WHO) regional adviser for health financing for the Eastern Mediterranean region, WHO health economist in Bangladesh, and World Bank senior health specialist for the East Asia and Pacific region. Olivia Corazon Z. Nieveras Senior Public Health Specialist (Healthier Populations), World Health Organization, Thailand Dr. Olivia is a medical doctor with training in business economics and public health. With over 20 years of experience, she has held technical and leadership roles with WHO and GIZ, and has worked closely with governments in Asia and Africa on universal health coverage, primary health care reforms, health financing, noncommunicable diseases, mental health, and determinants of health. She studied at the University of the Philippines and earned her medical degree from the University of the East Ramon Magsaysay Medical Center. Chanon Nusawat Consultant (Health and Medicine), Asian Development Bank Chanon Nusawat is a pharmacist and public health researcher specializing in health economics, clinical epidemiology, and health systems. He holds a Master of Public Health from the University of Tokyo and is currently a doctoral candidate in social medicine at the same institution. He previously served as a consultant for WHO Thailand, contributing to NCD monitoring and evaluation frameworks. His work focuses on integrating mental health and NCD services in primary health care and supporting evidence-informed policy in Asia and the Pacific. Vasoontara S. Yiengprugsawan Senior Universal Health Coverage Specialist (Service Delivery), Human and Social Development Office, Sectors Department 3, Asian Development Bank Dr. Vasoontara Yiengprugsawan oversees ADB's health technical assistance, including noncommunicable diseases and mental health and regional cooperation in the Greater Mekong Subregion and BIMP-EAGA. She has held senior health research positions in Australia, a WHO Fellowship with the Asia Pacific Observatory on Health Systems and Policies, and worked in policy and research with a UN Migration Agency in Geneva. She holds a PhD in Epidemiology from Australian National University and an MA in International Development from Syracuse University. Follow Vasoontara S. Yiengprugsawan on Leave your question or comment in the section below: View the discussion thread.