The longitudinal relation between loneliness and perceived stress: A structural equation modelling analysis of 10,159 individuals.

Aims: Prolonged loneliness and severe stress are increasingly recognised as public health concerns and considered risk factors for mental disorders, somatic illnesses and mortality. Loneliness and perceived stress also often co-occur; however, their longitudinal relation remains unclear. To the best of our knowledge, this is the first study aiming to investigate the longitudinal relation between loneliness and perceived stress independently of cross-sectional associations and time effects.

Methods: Designed as a population-based cohort study with repeated measurements, the present study included individuals aged 16-80 years at baseline who participated in the Danish National Health Survey ('How are you?') in 2013 and 2017 (N = 10,159; response rate = 50%). Structural equation modelling was used to examine associations between loneliness and perceived stress in the total sample and across age groups (i.e., 16-29, 30-64 and 65-80 years).

Results: The models indicated bidirectional relations between loneliness and perceived stress. The standardized cross-lagged path from loneliness to perceived stress (β: 0.12, 95% confidence interval (CI) (0.08, 0.16), p < 0.001) and from perceived stress to loneliness (β: 0.12, 95% CI (0.07, 0.16), p < 0.001) both corresponded to small effect sizes in the total sample. Additionally, the results indicated strong cross-sectional associations, especially among adolescents and young adults (16-29 years), and high temporal stability, especially among the elderly (65-80 years).

Conclusions: Loneliness and perceived stress mutually predict each other over time. The finding of both substantial bidirectional and cross-sectional associations demonstrates an interdependence between loneliness and perceived stress that may be relevant to consider in future interventions.