The role of social support in transdiagnostic symptom networks in affective and psychotic disorders: a cross-sectional and longitudinal network analysis.

Symptoms and psychosocial factors interact dynamically across affective and psychotic disorders, yet longitudinal evidence remains limited. Building on the network theory of psychopathology, this study conceptualizes mental disorders as systems shaped by symptom-environment interactions. Using data from a two-site German cohort (N = 2743), we examined 36 psychopathological symptoms and 11 psychosocial factors using cross-sectional and longitudinal analyses. At baseline, transdiagnostic symptom networks were estimated and compared between patients with affective or psychotic disorders (N = 1569) and healthy controls (N = 1174). In addition, a separate baseline network including both symptom and psychosocial nodes (N = 1462) was estimated to identify psychosocial bridge variables, and a temporal symptom-psychosocial cross-lagged panel network (N = 642) was used to examine prospective associations over a two-year follow-up. The baseline transdiagnostic symptom network was denser in patients than in healthy controls. In the baseline symptom-psychosocial network, perceived stress and social support emerged as key psychosocial bridge variables. In the longitudinal cross-lagged panel network, social support showed the strongest overall predictive associations with follow-up nodes among psychosocial variables. These findings suggest that social support may be closely linked to symptom-environment associations across affective and psychotic disorders and warrant further investigation as a potentially modifiable psychosocial factor in transdiagnostic intervention research.