Depression is a leading cause of disability worldwide and a major contributor to the global burden of disease, with a complex etiology involving genetic, environmental, and social factors(Peterson, 2021). Among the most significant risk factors is childhood adversity, which encompasses a range of traumatic experiences such as emotional abuse, physical neglect, and sexual abuse (Lindert et al., 2014). A substantial body of research has established a strong association between exposure to childhood adversity and an elevated risk of developing depression later in life, a relationship that persists even after accounting for various confounding variables (Watson et al., 2025). Key findings from the Adverse Childhood Experiences (ACE) Study have shown a dose-response relationship, where a greater number of childhood traumas significantly increases the likelihood of adult mental illness (Anda et al., 2006; Dube et al., 2002; Hughes et al., 2017; Webster, 2022). This link is further supported by large-scale population studies (Green et al., 2010), and its neurobiological basis is being increasingly understood, with research highlighting how early-life stress can alter brain structure and function, thereby increasing vulnerability to depression (Kuzminskaite et al., 2021; Teicher and Samson, 2016). The pervasive and long-lasting nature of this risk highlights the urgent need to identify modifiable factors that might mitigate the psychological impact of early-life trauma.

While the detrimental effects of childhood adversity are well-documented, less is known about the protective mechanisms that may buffer its long-term mental health consequences. A growing body of evidence suggests that healthy lifestyle factors, including adequate sleep, regular physical activity, and strong social connections, are independently associated with improved mental well-being and a lower risk of depression(Li and Hao, 2025; White et al., 2024). These factors are known to promote resilience and support mental health through various pathways, such as reducing inflammation, regulating the stress response system, and enhancing neuroplasticity (McMahon et al., 2025; Penedo and Dahn, 2005).Furthermore, the protective role of social support has been a key area of focus, with research consistently showing that strong social connections can significantly mitigate the psychological impact of early trauma and reduce the risk of later-life depression (Acoba, 2024; Calhoun et al., 2022). Similarly, interventions focused on physical activity have been shown to be effective in managing depressive symptoms, even in populations with a history of trauma (Bellón et al., 2021; Cody et al., 2022; Rowland et al., 2023; Xiao et al., 2025). However, the combined effect of these healthy lifestyle factors, particularly within the context of individuals with a history of childhood adversity, remains an important and under-researched area. Understanding whether a healthy lifestyle can act as a buffer against the enduring effects of childhood trauma could offer new avenues for prevention and intervention.

To address this critical knowledge gap, we conducted a large-scale prospective cohort study. The primary objective of our research was to investigate the associations between different types of childhood adversity, specific healthy lifestyle factors, and the incidence of depression. Specifically, we aimed to: 1) confirm the association between childhood adversity and depression incidence; 2) examine a potential dose-response relationship between the number of healthy lifestyle factors and depression risk; and 3) explore the specific protective effects of individual lifestyle factors in this vulnerable population. We hypothesized that a greater number of healthy lifestyle factors would be associated with a lower risk of depression, even among individuals with a history of childhood adversity. Our findings provide compelling evidence that a healthy lifestyle serves as a powerful protective factor against depression in individuals who have experienced childhood adversity. These results have significant public health and clinical implications, underscoring the potential for lifestyle-based interventions to improve long-term mental health outcomes in this vulnerable population.