Background: There is a well-established association between diabetes and depression, and recent evidence suggests that the strength of this association may be stronger in Ireland than in other European countries. A cross-sectional study found that, out of 19 European Countries, Ireland had the highest odds of depression in individuals with versus without diabetes. However, prospective research is lacking. It remains unclear if, in Ireland, those with diabetes are more vulnerable to depression, those with depression have an increased risk of diabetes, or both, compared to other countries. Knowledge of the predictors of international differences in diabetes-depression comorbidity is also needed for appropriate mitigation strategies to be developed.
Aims: The project will pool data from prospective cohort studies to 1) investigate international differences in the prospective bi-directional associations between depression and diabetes comorbidity risk in Europe, and 2) investigate country-and participant-level factors that predict international differences in comorbidity.
Methods: Data from The Irish Longitudinal Study on Ageing (TILDA) and public datasets including The English Longitudinal Study of Ageing (ELSA) and The Survey of Health, Ageing and Retirement in Europe (SHARE) will be used. Country-level predictors such as access to and provision of diabetes care, and participant-level predictors such as sociodemographic characteristics, health behaviours, stress, and other comorbidities, will be examined. Multilevel models will estimate the bidirectional risk of depression and diabetes comorbidity within and between countries and examine predictors of comorbidity.
Implications: This project is a collaboration between researchers, knowledge users, and people with diabetes, pooling data from Europe/UK longitudinal cohorts, and addresses a major public health challenge in Ireland. Independently, diabetes and depression are significant contributors to global disease burden, and jointly they pose even greater health threats. Understanding predictors of international differences has the potential to shape future public health interventions in Ireland and internationally.
