Depression, as one of the most prevalent mental disorders in the United States, has a significant economic impact. With its increasing global prevalence, it is projected to have a greater effect on disability-adjusted life years by 2020 (Whiteford et al., 2013). Research indicates that in 2019, 7.8 % of U.S. adults experienced at least one major depressive episode (SAMHSA, 2020). Depression is associated with higher rates of mortality, disability, and diminished quality of life. Moreover, it can exacerbate comorbid conditions such as diabetes (Ludman et al., 2004). Despite extensive research, the exact cause of depression remains unclear, treatment options are limited, and depression may often go unnoticed in adults.

Aiming to reduce health disparities, improve health outcomes, and enhance the overall well-being of the population (Gómez et al., 2021), the U.S. Healthy People 2030 Commission defines social determinants of health (SDoH) as the conditions in the environments where individuals are born, live, learn, work, play, worship, and age that influence health and well-being outcomes, functioning, quality-of-life outcomes, and risks (HHS., 2020). The SDoH comprise five main domains: economic stability, education access and quality, health care access and quality, neighborhood and built environment, and social and community context (Liang et al., 2024). While well-established inherent risk factors play a significant role in the prevalence of depression, SDoH are also recognized as contributing factors to disparities in depressive outcomes, particularly in communities of racial and ethnic minorities (Yelton et al., 2022). SDoH stands out as the most significant modifiable risk factor for the development of depression symptom (Califf et al., 2022). Studies consistently indicate that insufficient insurance coverage, income inequality, and education disparities may account for the increased prevalence of depression symptom in certain sociodemographic groups (Dicola et al., 2013; Patel et al., 2018; Wickersham et al., 2021). Moreover, there is growing concern regarding the correlation between depression symptom and multiple adverse SDoHs experienced by individuals. This means that individuals may face various unfavorable SDoHs concurrently, compared to their peers, which heightens their risk of developing depression symptom.

Understanding the SDoH is crucial for addressing the risk of depression in adulthood, as this modifiable factor plays a significant role in various triggers that contribute to mental health issues. However, the connection between SDoH and the prevalence of depression symptom in the overall adult population remains unclear. While there is growing evidence suggesting a relationship between individual SDoH and depression symptom, previous studies have only focused on isolated determinants (Dicola et al., 2013; Wickersham et al., 2021). The complexity of various SDoH and their potential interactions with other socioeconomic factors at different geographic levels can complicate the accurate comparison of the effects of multiple unfavorable SDoHs. Additionally, previous research has not extensively explored how different SDoHs impact depression symptom and their potential role in gender and racial/ethnic disparities within a representative sample. To date, there is a lack of comprehensive studies investigating the primary SDoHs contributing to depression symptom among the general adult population. This study aims to address the research gap by analyzing data from a nationally representative survey conducted in the U.S. from 2005 to 2018. It investigates the impact of various SDoHs on self-reported depression symptom and delves into the relationship between the accumulation of adverse SDoHs within individuals and the presence of depression symptom.