Within‐person dual‐pathway model linking optimism to depression: A random‐intercept cross‐lagged panel study of cognitive bias and loneliness among Chinese university students

This 1-year longitudinal study applied a random intercept cross-lagged panel model (RI-CLPM) to examine how optimism influences depression through negative cognitive bias and loneliness among Chinese college students, disentangling within-person processes from stable between-person differences. 886 college students completed the Beck Depression Inventory, Optimism Scale, Negative Cognitive Bias Questionnaire and UCLA Loneliness Scale at three time points over 1 year. (1) All four variables (optimism, negative cognitive bias, loneliness, depression) were significantly correlated across three time points (p < .001). (2) RI-CLPM revealed: within-person surges in optimism predicted lower negative cognitive bias (β = -.28, p < .001) and loneliness (β = -.35, p < .001) at the next wave; these reductions predicted lower depression (β = .36 and .41, p < .001). Mediation was partial through negative cognitive bias (indirect β = -0.11, 95% CI [-0.18, -0.05]) but complete through loneliness (indirect β = -0.15, 95% CI [-0.23, -0.08]). Optimism at T1 negatively predicted negative cognitive bias and loneliness at T2, which positively predicted depression at T3. After accounting for between-person variability, within-person increases in optimism predicted subsequent decreases in depression through two concurrent pathways: negative cognitive bias and loneliness.