Mental disorders were acknowledged as the primary contributors to the burden of disease, accounting for 1566.2 disability-adjusted life years (DALYs) per 100,000 individuals on a global scale in 2019 (The Lancet Psychiatry, 2022). Among these mental disorders, depressive disorders (including major depressive disorder and dysthymia) and anxiety disorders were the most prevalent, constituting 37.3 % and 22.9 % of the total DALYs attributed to mental disorders, respectively (The Lancet Psychiatry, 2022). The burden of mental disorders spanned across an individual’s entire lifespan, impacting various aspects of their lives.

By 2030, one-sixth of the global population was projected to be 60 years or older (World Health Organization). As the older population increased, the prevalence of depression and anxiety disorders in this group was becoming a growing concern. Biological factors associated with aging and disease, such as physical decline, vitamin deficiencies and atherosclerosis (Maier et al., 2021), genetic predisposition as well as social- psychosocial stressors including economic adversity, social isolation, and bereavement (Alexopoulos, 2005; Maier et al., 2021; Hammen, 2018), might render older adults more susceptible to depression and anxiety disorders. Moreover, depression and anxiety disorders imposed a substantial burden on the older adults, not only aggravated chronic diseases (e.g., increased the risk of cardiovascular events and premature mortality (Momen et al., 2020; Leone et al., 2021)), but also potentially impaired cognitive function and increased the risk of dementia (Modrego et al., 2023). These issues intensified the emotional distress and economic strain on individuals and their families, concurrently contributing to a surge in societal medical expenditures and caregiving demands. Consequently, it was imperative to strengthen the attention towards depression and anxiety disorders in older adults, while simultaneously advancing the development of mental health services tailored to this vulnerable group.

Current research on depression and anxiety disorders in older adults was not comprehensive, with only a few studies that focused on the burden and trends of mental disorders in older adults and assessed differences across countries and regions of the world (Byers et al., 2010; Ogbo et al., 2018). A study revealed the prevalence of depression in older adults globally but did not delve into differences between regions (Barua et al., 2011). Similarly, Ladin investigated the correlation between depression and economic inequality in older adults, with comparisons limited to Southern and Nordic countries (Ladin et al., 2009). Moreover, research on anxiety in later life was disproportionately scarce compared to depression-related literature (Am. J. Psychiatry, 1994).

In summary, current research on depression and anxiety disorders in the older adults is incomplete. There is a lack of research that assesses the differences in the burden of psychological disorders among the older adults in different regions from a global perspective, and research on anxiety disorders in the older adults is also relatively scarce. Therefore, this study aims to: (1) examine the global burden and trends of depression/anxiety disorders among older adults from 1990 to 2019, with a focus on focusing on gender and age disparities; (2) elucidate age, period, and cohort effects influencing these disorders; and (3) characterize their spatial distribution to identify high-burden regions. These findings will provide updated epidemiological evidence on the global burden of depression and anxiety in older adults, thereby offering crucial insights to inform targeted intervention measures and policy optimization.