Network relationships among depressive symptoms, sleep quality, and frailty in Chinese older adults: an undirected and bayesian network analysis

Depressive symptoms, sleep disturbances, and frailty significantly affect older adults, representing a substantial public health issue. Although previous studies have demonstrated complex interrelationships among these factors, the underlying causal pathways and optimal intervention targets remain unclear. The study aimed to elucidate the potential causal pathways linking these factors and identify optimal intervention targets to mitigate their synergistic effects. A cross-sectional study was conducted in 2022 among 3,924 Chinese adults aged ≥ 60 years. Frailty was assessed using the FRAIL scale; sleep quality via the Brief Pittsburgh Sleep Quality Index; and depressive symptoms with the Patient Health Questionnaire-9. We employed network and Bayesian analyses to examine the interactions among these factors, focusing on identifying core and bridge symptoms and potential causal directions. Our findings indicate that illness (rs=2.30, rc=0.01, rb=24) has the greatest centrality, while fatigue (rBEI = 0.417) serves as the primary bridge symptom. Network comparison tests showed no significant differences in structure based on gender, age, or residence, suggesting uniformity across groups (p > 0.05). Sleep disturbances emerged as the most influential factor in the network, directly impacting both sleep quality and frailty. This study uncovers the complex links between depressive symptoms, sleep quality, and frailty in older adults. Illness and fatigue are key symptoms, with sleep disturbances identified as a primary predictor affecting both sleep quality and frailty. Targeting sleep disturbances may alleviate frailty and enhance overall sleep health.