Mild cognitive impairment (MCI) has been associated with diabetes mellitus (DM) with earlier onset, longer duration, and greater severity, according to an article released on August 11, 2008 in the Archives of Neurology, one of the JAMA/Archives journals.
As the transitional stage between the effects of aging and dementia itself, much interest has been placed in this stage as a potential warning indicator for Alzheimer’s and cognitive disorders. Previously, an association has been shown between diabetes and mild cognitive impairment. According to the background information in the article, poor management of glucose levels may, over time, lead to neuronal death. Additionally, the increased risk of cardiovascular disease and diabetes associated with diabetes may also increase the risk of cognitive impairment.
To investigate the relationship between mild cognitive impairment and diabetes, Rosebud O. Roberts, M.B.Ch.B., M.S., and colleagues at the Mayo Clinic, examined subjects between the ages of 70 and 89 on October 1, 2004 in the Olmstead County, Minnesota. Each subject underwent a neurological exam, blood glucose test, and an interview with questions related to diabetes history, treatment, and complications. To verify medical history, a medical records linkage system was consulted.
In total, 329 patients showed mild cognitive impairment and 1,640 without. In comparing these two groups, diabetes rates were similar at 20.1% and 17.7% respectively. However, in the group with the impairment, diabetes was more likely to develop before the age of 65, have it for 10 years or more, of receiving insulin treatments, and of having various complications of diabetes.
The authors indicate that this progression is biologically plausible: “Severe diabetes mellitus is more likely to be associated with chronic hyperglycemia [high blood glucose], which, in turn, increases the likelihood of cerebral microvascular disease and may contribute to neuronal damage, brain atrophy and cognitive impairment,” they say. The association between eye disease diabetic retinopathy with mild cognitive impairment could support this theory, as damage to brain blood vessels could contribute to cognitive problem development.
The authors conclude: “Our findings suggest that diabetes mellitus duration and severity, as measured by type of treatment and the presence of diabetes mellitus complications, may be important in the pathogenesis of cognitive impairment in subjects with diabetes mellitus.” They continue: “In contrast, late onset of diabetes mellitus, short duration of diabetes mellitus or well-controlled diabetes mellitus may have a lesser effect.”
Association of Duration and Severity of Diabetes Mellitus With Mild Cognitive Impairment
Rosebud O. Roberts, MBChB, MS; Yonas E. Geda, MD; David S. Knopman, MD; Teresa J. H. Christianson, BS; V. Shane Pankratz, PhD; Bradley F. Boeve, MD; Adrian Vella, MD; Walter A. Rocca, MD, MPH; Ronald C. Petersen, MD
Arch Neurol. 2008;65(8):1066-1073.
Written by Anna Sophia McKenney