Predictors of cognitive decline in older people with diabetes

Abstract

Objective: To determine longitudinal predictors of cognitive decline in non-demented older people with diabetes.

Research Design and Methods: Cognitive assessments were performed in 205 subjects with diabetes (mean age 75.3 years) and repeated a median 1.6 years later. The sample was drawn from an existing cohort study and data on diabetes, cardiovascular risk factors and complications were collected 7.6±1.1 years prior and at the time of the initial cognitive assessment. Cognitive status was defined using the Clinical Dementia Rating (CDR) scale and cognitive decline was defined by change in CDR.

Results: The sample included 164 subjects with normal cognition (CDR = 0) and 41 with cognitive impairment without dementia (CDR = 0.5). At follow-up, 33 (16.1%) had experienced cognitive decline (4 new dementia cases, 29 to cognitive impairment without dementia). Only educational attainment predicted cognitive decline from the data collected 7.6 years prior to cognitive assessment. Univariate predictors of cognitive decline at the time of first cognitive assessment included age, education, urinary albumin/creatinine ratio (ACR) and treatment with either ACE inhibitors (ACEI) or angiotensin receptor blockers (ARB). With multiple logistic regression controlling for age and education, cognitive decline was predicted by natural logarithm ACR (Odds ratio (95% CI): 1.37 (1.05-1.78), P=0.021) whilst treatment with either ACEI or ARB was protective (0.28 (0.12-0.65), P=0.003).

Conclusions: In this sample of older patients with diabetes, microalbuminuria was a risk factor for cognitive decline whilst drugs that inhibit the renin-angiotensin system were protective. These observations require confirmation because of their considerable potential clinical implications.