Type 2 diabetes mellitus and depression in two large population-based cohorts. Causal or concurrent co-morbidity?
10 / 2000 - 10 / 2003
[BACKGROUND:] Depression in people with diabetes is increasingly recognized as a major health problem. It was found, mainly in studies carried out in the USA, that the prevalence of depression is approximately three times higher in people with diabetes, compared to the general population. Relevant data for the Netherlands are still lacking. Depression not only interferes with the quality of life of people with diabetes, but also negatively affects their adherence to treatment and their glycaemic control. Depression was also found to be associated with increased development of long-term complications of diabetes. Yet, the direct relationship between type 2 diabetes and depression remains unclear. Although there are many findings suggesting reciprocal causal mechanisms, involving both physiological and psychological pathways, the evidence is often based on cross-sectional studies suffering from serious conceptual and methodological shortcomings. [OBJECTIVES:] 1) To determine the prevalence and incidence of depression in people with and without type 2 diabetes in the Netherlands, using data from two large population-based cohorts (the Hoorn Study and the Longitudinal Aging Study Amsterdam [LASA]). 2) To explore sociodemographic, psychological and physiological risk factors for the development of depression symptomatology in people with type 2 diabetes. [METHODS:] The incidence and prevalence of depression in people with diabetes will be studied in participants in either the Hoorn Study or LASA. A cross-validation design will be used to investigate risk factors for depression in a longitudinal study. Subjects will be randomly assigned to group A or group B. Using data on group A, stepwise regression analyses will be applied to select significant predictors of depression. In group B, Structural Equation Modelling techniques will be used to test the model(s) developed in group A. [RESULTS.] The study was initiated in November 2000. Results of a review of the literature suggest that the intake of omega-3 polyunsaturated fatty acids may partly explain the positive association between diabetes and depression.