Unequal Resilience: Socioeconomic Disparities in Mental Health Trajectories and the Role of Social Capital During the COVID-19 Pandemic—Longitudinal Evidence from Japan

While the social and economic impact of the COVID-19 pandemic received significant attention in its early phase, few empirical studies have examined how it influenced the trajectory of mental well-being over time. This study analyses longitudinal changes in mental well health in Japan during the first two years of the pandemic using data from two online panel surveys conducted between June 2020 and March 2022. Applying hierarchical linear regression and two-way fixed effects models, we analyse how mental well-being developed comparing income groups and look at the role of changes in social capital for mental health resilience. Preexisting socioeconomic disparities in mental health, with individuals in the lower-income strata experiencing lower well-being, persisted throughout the period under study, but were exacerbated by income-based differences in how the economic and social consequences unfolded over time, resulting in divergent health trajectories. While higher-income individuals maintained relatively stable mental well-being throughout, mental health among the lowest-income group was more strongly affected by the negative economic impact of the pandemic, compounded by stratified effects of changes in social capital. As a result, mental health among low-income individuals recovered only in late 2021, narrowing—but not eliminating—the mental health gap. Social capital resources (including face-to-face and remote communication, social support availability, general social trust, and trust in the government) played a crucial role in mitigating mental health impacts across all income groups, although with distinct patterns. In the early phase of the pandemic, reduced face-to-face communication was particularly detrimental for economically vulnerable individuals. Their mental health recovery in late 2021 was largely driven by increased general social trust and, notably, regained trust in the government. Our findings underscore the need to address both economic insecurity and social disconnection to contain mental health inequality during crises. While strengthening social ties is an important aspect of this, ensuring credible and effective crisis management by governments and public institutions—along with measures that mitigate the economic fallout of such crises—seems most critical to minimize the mental health impact of large-scale disruptions, particularly among vulnerable groups.