Prospective associations between diabetes and depressive symptoms across European regions: a secondary analysis of ELSA, TILDA, and SHARE datasets

This article investigates predictive associations between diabetes and depressive symptoms across Ireland, the United Kingdom, and four European regions. The data were obtained by merging datasets from three large prospective cohort studies-the English Longitudinal Study on Ageing, The Irish Longitudinal study on Ageing, and the Survey on Health, Ageing and Retirement in Europe. We first applied a survival analysis design to two samples of 43 061 and 35 993 participants, investigating elevated depressive symptoms as a risk factor for diabetes, and diabetes as a risk factor for elevated depressive symptoms, respectively. We next applied a multilevel modeling approach to examine depressive symptoms before, during, and after diabetes onset across 101 799 participants. We found a bidirectional association between diabetes and depressive symptoms; however, the strength of these associations did not significantly differ between the regions (P > .01). The results also showed that individuals with newly diagnosed diabetes consistently reported higher depressive symptoms than those without diabetes, even before diagnosis. However, we observed no country-specific differences in the gradual changes in depressive symptoms regardless of participants' diabetes status. Diabetes at baseline was associated with higher risk of developing depression; and vice versa. These associations were not moderated by geographical location. Therefore, the risks of diabetes and depressive symptoms comorbidity seem to be equal across all observed geographic regions.