Loneliness, Teacher-Student Closeness, and Academic Achievement: A Longitudinal Study in Early Adolescence

Background: Loneliness is a risk factor impacting adolescents’ adjustment; however, the mechanisms underlying its effects on school performance are unclear. Prior research has predominantly employed cross-sectional methodologies, thereby limiting insights into the longitudinal processes that connect loneliness with academic success. The quality of teacher–student relationships (TSR), especially teacher–student closeness (TSC), may serve as a pivotal mediating factor within this relationship. Purpose: This study examined whether TSC mediates the longitudinal association between loneliness and academic achievement in early adolescents. Methods: The sample consisted of 314 Italian junior high school students (Mage = 12.28, SD = 0.83, 51.9% female) who participated at two time points during the 2024–2025 school year. Loneliness and TSC were assessed through validated self-report questionnaires, while academic achievement was obtained from school records. Longitudinal data were analyzed using latent autoregressive cross-lagged panel models to test direct and indirect effects, controlling for sex, age, and cultural possessions. Results: Loneliness at T1 negatively predicted TSC at T2 (β = –.125, p = .006), whereas TSC at T1 positively predicted academic achievement at T2 (β = .212, p = .001). The direct effect of loneliness T1 on academic achievement T2 was not significant, while the indirect effect through TSC was significant (bootstrap = 5000, estimate = –0.034, 95¼CI [–0.067, –0.002]), indicating full mediation. Conclusions: The findings suggest that loneliness indirectly influences academic achievement by undermining teacher–student closeness. TSC thus emerges as a key protective factor for adolescents’ academic and socio-emotional development.