The effect of loneliness on depressive symptoms in the 65+ European population: A longitudinal observational study using SHARE data

Abstract Objectives: Loneliness has been found to be associated with an increased probability of depressive symptoms in various research studies. Yet, the relationship is complex, and it remains unclear whether loneliness is a cause for depressive symptomatology. This study aims to investigate the possible causal effect of loneliness in the loneliness-depressive symptoms relationship among 65+ older adults in Europe. Method: This study analyzed two waves of observational data (2015–2017) from the Study of Health, Aging and Retirement Europe (SHARE) (n = 6808 individuals) and tried to identify a causal effect of direct and indirect loneliness on depressive symptomatology by accounting for confounding of potential unmeasured factors underlying the relationship using an endogenous treatment-effects model. Results: This study showed that there was a substantial positive association between loneliness in 2015 and new depressive symptoms in 2017 in the sample. However, there was no support for the hypothesis that loneliness in 2015 was a cause of depressive symptoms among those adults in 2017. In addition, there was limited evidence for unmeasured factors confounding the relationship. Discussion: Loneliness may not be a cause for depressive symptoms. This suggests that there might be other reasons why lonely individuals are at an increased risk of depressive symptoms. Therefore, a shift in focus when aiming to reduce depressive symptoms among lonely older adults may be warranted.