Posted on Jul 10, 2012, 6 a.m.
People with diabetes experienced significantly worse cognitive decline over a 9-year period, and progressively higher HbA1c further contributed to the impairments.
Inflammation is a chronic biological process that may contribute to cognitive decline. Kristine Yaffe, from the University of California San Francisco (UCSF; California, USA), and colleagues conducted the prospective Health, Aging, and Body Composition (Health ABC) Study at two community clinics, totaling 3,069 patients whose mean age was 74.2 at the study’s start. Participants completed a standardized assessments for mental health and cognitive performance, at baseline and at specific intervals over the following 10 years. They also had their HbA1c levels measured at baseline, and 4, 6, and 10 years later. At the start of the study, 23.4% of patients had diabetes, and 159 people, or 5.2%, developed diabetes over the course of the study. The researchers found that at baseline, those with diabetes had significantly lower scores on both tests of cognitive function than those without the disease. After 9 years, the team observed a greater cognitive decline among those who had diabetes at baseline than those who didn't have diabetes. Further, the researchers also found that among patients who were diabetic at the study's start, higher HbA1c – a marker of inflammation – levels achieved lower mean cognitive scores. Over about 3.5 years, patients with a mid-range (7% to 8%) or high (8% or up) HbA1c level had significantly lower mean cognitive scores than those with a low level (7% or less). Observing that: " Among well-functioning older adults, [diabetes mellitus] and poor glucose control among those with [diabetes mellitus] are associated with worse cognitive function and greater decline," the study authors conclude that: "This suggests that severity of [diabetes mellitus] may contribute to accelerated cognitive aging.”
Yaffe K, Falvey C, Hamilton N, Schwartz AV, Simonsick EM, Satterfield S, et al. “Diabetes, Glucose Control, and 9-Year Cognitive Decline Among Older Adults Without Dementia Diabetes and Risk of Cognitive Decline.” Arch Neurol. 2012 Jun 18:1-6.