Joint trajectories of loneliness and depressive symptoms and risk of incident osteoporosis among middle-aged and older adults: a prospective cohort study

Background Loneliness, depressive symptoms, and osteoporosis are major public health concerns in ageing populations worldwide. Although the interplay between mental and physical health is well recognized, evidence remains limited regarding whether long-term joint patterns of loneliness and depressive symptoms are prospectively associated with incident osteoporosis. This study aimed to investigate the prospective associations between joint trajectories of loneliness and depressive symptoms and incident osteoporosis in middle-aged and older adults using a nationally representative cohort. Methods Data were obtained from the English Longitudinal Study of Ageing (ELSA). A total of 4,117 participants aged ≥50 years who were free of osteoporosis at Wave 4 were included. Group-based multi-trajectory modelling was used to identify joint trajectories of loneliness, assessed by the UCLA Loneliness Scale, and depressive symptoms, assessed by the Center for Epidemiologic Studies Depression Scale (CES-D), across Waves 2 to 4. Incident osteoporosis was defined as self-reported physician-diagnosed osteoporosis during follow-up from Waves 5 to 9. Cox proportional hazards models were used to examine the associations between trajectory group membership and the risk of incident osteoporosis after adjusting for sociodemographic characteristics, health status, and lifestyle factors. Results Three distinct joint trajectories of loneliness and depressive symptoms were identified: a low loneliness/low depressive symptoms stable group (70.83%), a moderate loneliness/low depressive symptoms group (21.54%), and a persistent high loneliness/high depressive symptoms group (7.63%). During follow-up, 276 participants developed osteoporosis. In the fully adjusted model, compared with the low loneliness/low depressive symptoms stable group, participants in the persistent high loneliness/high depressive symptoms group had a significantly higher risk of incident osteoporosis (HR = 1.97, 95% CI: 1.37–2.83; P  P  = 0.002). Conclusion Persistent loneliness and depressive symptoms were associated with a higher risk of incident osteoporosis among middle-aged and older adults. These findings indicate that psychological well-being may be relevant to osteoporosis risk assessment and healthy ageing, while not establishing a causal relationship.