Longitudinal Interrelations Among Loneliness, Depressive Symptoms, and Social Behaviors in Youth: A Cross-Lagged Panel Study in a Post-Disaster Context.

Loneliness is a significant public health concern among children and adolescents and is closely linked to psychosocial adjustment issues. However, the longitudinal associations among loneliness, depressive symptoms, aggressive behavior, and prosocial behavior remain underexplored. Through the developmental cascade framework, this study examined the reciprocal relationships among these variables using a three-wave cross-lagged panel model. The sample comprised 634 students (47.8% boys) in grades 3-9 from Wajima City, Japan, a region severely affected by the 2024 Noto Peninsula Earthquake. Instead of age the sex level was used to index the developmental stage. The sample was ethnically homogeneous and consisted of Japanese participants. Data were collected between July 2024 and February 2025 using validated self-report measures. Bidirectional associations were observed between loneliness and depressive symptoms; however, depressive symptoms showed stronger and more consistent associations with subsequent levels of loneliness (β = 0.15-0.23, ps < 0.001) than the reverse pathway (β = 0.06-0.08, ps = 0.021-0.095). Aggressive behavior was positively associated with later levels of loneliness (β = 0.08-0.09, ps < 0.05) and negatively associated with subsequent levels of prosocial behavior (β = -0.11 to - 0.12, ps < 0.01). Meanwhile, longitudinal associations of prosocial behavior were limited, including a small positive association with subsequent loneliness (β = 0.08, p = .043). The findings support the developmental cascade framework, highlighting the interconnected influences of emotional, behavioral, and social-cognitive processes. These results underscore the importance of integrative, multi-domain approaches to understand and support youth psychosocial adjustment, particularly in post-disaster contexts.