SALT LAKE CITY—Patients with Alzheimer’s disease who have comorbid diabetes experience an earlier onset of cognitive impairment and a faster rate of cognitive decline than those without diabetes, according to a study presented at the 133rd Annual Meeting of the American Neurological Association.
Paul E. Schulz, MD, Associate Professor of Neurology, Neuroscience, and Translational Biology at Baylor College of Medicine in Houston, and colleagues reviewed the charts of patients with Alzheimer’s disease from the Michael E. DeBakey VA Medical Center in Houston between May 2003 and January 2007. The final analysis included 16 patients with Alzheimer’s disease and comorbid diabetes and 40 patients with Alzheimer’s disease alone. “We excluded about 80% of the diabetics with Alzheimer’s disease from this study because they had vascular changes on their MRI,” Dr. Schulz noted. All participants underwent a set of standardized neuropsychologic tests, including list learning, recognition, and delayed recall; story learning and delayed recall; lexical and animal fluency; the Boston naming test; Trails A and B and digit span; and the Mini-Mental State Examination (MMSE).
Patients with Alzheimer’s disease and comorbid diabetes started to have memory problems 10 years earlier than did the control group (mean age, 75 vs 85). The contrast in monthly decline in MMSE scores was also significant—about 0.5 in those with diabetes, compared with about 0.1 in controls. A greater prevalence of hypertension and hyperlipidemia in the diabetic group also contributed to the observed faster cognitive deterioration. In addition, patients with Alzheimer’s disease and comorbid diabetes had poorer performance on certain individual neuropsychologic tests.
“We found preliminarily that patients with diabetes may have an earlier age of onset for Alzheimer’s disease,” Dr. Schulz told Neurology Reviews. “Hence, physicians might screen diabetics for Alzheimer’s disease at an earlier age than their patients without diabetes.”
One caveat, however, is that by excluding patients with vascular changes on MRI, there could have been an inadvertent bias. Hence, it will be important to investigate patients with Alzheimer’s disease of the same age to affirm that those with diabetes progress more rapidly, Dr. Schulz concluded.
—Laura Sassano