Type 2 diabetes and depression via microvascular dysfunction, neurodegeneration, inflammation, advanced glycation end products ( <scp>AGEs</scp> ), and arterial stiffness
Indra L. M. Steens, Miranda T. Schram, Alfons J.H.M. Houben, Tos T. J. M. Berendschot, Jacobus F. A. Jansen, Walter H. Backes, Annemarie Koster, Hans Bosma, Simone J. P. M. Eussen, Bastiaan E. de Galan, Thomas T. van Sloten
Abstract
AIMS: Type 2 diabetes increases the risk of depression, but the mechanisms underlying this association are incompletely understood. We investigated whether microvascular dysfunction, neurodegeneration, low-grade inflammation, advanced glycation end products (AGEs) and arterial stiffness, pathologies that are more common in diabetes, explain, or mediate the association between type 2 diabetes and incident clinically relevant depressive symptoms. MATERIALS AND METHODS: We used prospective data from The Maastricht Study, a population-based cohort study. Diabetes status and potential mediators were assessed at baseline. Clinically relevant depressive symptoms (PHQ-9 score ≥10) were assessed at baseline and each year during a median of 8.1 (IQR 4.2, 10.1) years of follow-up. Mediation analysis was employed to investigate the mediating effect of microvascular dysfunction (retinal, blood and MRI biomarkers), neurodegeneration (retina and MRI biomarkers), low-grade inflammation (blood biomarkers), AGEs (skin and blood biomarkers) and arterial stiffness (tonometry and ultrasound biomarkers). RESULTS: Data of 6091 participants (age, 59.4 years [SD 8.6]; 51.3% women; 23.6% type 2 diabetes) were available. Type 2 diabetes was associated with a higher incidence of clinically relevant depressive symptoms (HR:1.37; 95% CI 1.13, 1.65). This association was partly mediated by microvascular dysfunction (proportion mediated:10.4% [95% CI:3.6%, 17.2%]); neurodegeneration (proportion mediated:12.1% [95% CI: 3.9%, 20.3%]); AGEs (proportion mediated:5.4% [95% CI: 3.0%, 8.8%]); and arterial stiffness (proportion mediated:8.4% [95% CI: 3.3%, 13.5%]); but not by low-grade inflammation. CONCLUSIONS: The association between type 2 diabetes and a higher risk of clinically relevant depressive symptoms is partly mediated by microvascular dysfunction, neurodegeneration, AGEs and arterial stiffness.