The Longitudinal Relationship Between the Symptoms of Depression and Perceived Stress Among Chinese University Students.

Depression is one of the most common mental disorders. Perceived stress is a significant trigger and has adverse effects on depression. The complex longitudinal relationship between perceived stress and depression at the symptom level has significant implications for clinical intervention but is understudied. In our study, 823 students (67% female, median age 20.38, IQR 19.42-21.43) from a university in Tianjin were randomly sampled and completed measures of PHQ-9 and PSS-10, while 393 (65% female, median age 20.42, IQR 19.46-21.45) were followed up at three points, six months apart. The longitudinal relationships were estimated using cross-lagged modelling and cross-lagged panel network modelling. Among them, 49 students (59% female, median age 19.48, IQR 18.76-20.12) participated in resting-state functional magnetic resonance imaging (fMRI) scans. Cross-lagged analyses showed that depression and perceived stress predicted each other at the global level. At the dimensional level, depression and perceived helplessness were mutually predictive, while depression and perceived coping did not. In the cross-lagged panel network analyses, we identified symptoms in the top 20% of Bridge Expected Influence as bridging symptoms, specifically 'Guilt' (PHQ6) and 'Felt nervous and stressed' (PSS3). Notably, 'guilt' consistently demonstrated the highest Bridge Expected Influence across all time points and showed the strongest predictive power for perceived stress. We found that fALFF in the left superior frontal gyrus (SFG) mediated the association between "guilt" and perceived stress. Our findings elucidate the bidirectional relationship between symptoms of depression and perceived stress, identifying guilt is the most critical symptom of depression for the followed perceived stress, with SFG activity mediating this association.