Diabetes and Coronary Artery Disease as Risk Factors for Dementia.

ABSTRACT

AIM: Diabetes is associated with increased risk of dementia, but it is still debated to which degree this risk depends on the presence of atherosclerotic cardiovascular disease. We hypothesized that patients with diabetes and co-existing coronary artery disease (CAD), as a marker of systemic atherosclerotic cardiovascular disease, have substantially higher risk of developing dementia. METHODS: Patients ≥65 years, who underwent coronary angiography were stratified by diabetes and CAD. Outcomes were all-cause dementia, Alzheimer's dementia, and vascular dementia. We estimated adjusted hazard ratios (aHRs) using patients with neither diabetes nor CAD as a reference. RESULTS: A total of 103,859 patients were included. Of these, 23,189 (22%) had neither diabetes nor CAD, 3,876 (4%) had diabetes, 61,020 (59%) had CAD, and 15,774 (15%) had diabetes and CAD. During a median follow-up of 6.3 years, 5,592 (5.5%) patients were diagnosed with all-cause dementia. Patients with diabetes and CAD had the highest hazard rate of all-cause dementia (aHR 1.37, 95% CI 1.24-1.51), including Alzheimer's dementia (aHR 1.41, 95% CI 1.23-1.62) and vascular dementia (aHR 2.03, 95% CI 1.69-2.45). Patients with diabetes alone (aHR 1.14, 95% CI 0.97-1.33) or CAD alone (aHR 1.11, 95% CI 1.03-1.20) had a modestly increased rate of all-cause dementia. CONCLUSION: The combination of diabetes and CAD is associated with increased rate of dementia, in particular vascular dementia, suggesting that the diabetes-related risk of dementia is partly mediated through concomitant atherosclerotic cardiovascular disease. This underscores the importance of atherosclerotic cardiovascular disease prevention in diabetes patients to reduce cognitive decline.

We used national Danish healthcare registries to follow 103,859 patients examined by coronary angiography for up to 10 years to estimate the risk of dementia associated with diabetes and/or coronary artery disease. We found that diabetes and coronary artery disease are, separately, only modest risk factors of dementia. However, diabetes and coronary artery disease in combination were associated with highest risk of dementia, in particular vascular dementia. Out results suggests that the risk of dementia associated with diabetes is partly mediated through the presence atherosclerotic cardiovascular disease, which underscores the importance of atherosclerotic cardiovascular disease prevention in diabetes patients to reduce the risk of cognitive decline.