Last September, we covered the results of a Japanese study that found a link between diabetes and Alzheimer s disease. Now, new research published in the Archives of Neurology provides further evidence that diabetes may indeed lead to a higher risk of and a more rapid decline in cognitive function.
The latest prospective study, led by researchers from the University of California, San Francisco, followed over 3,000 patients with a mean age of about 74. At baseline and at certain intervals during the course of the 10-year study period, participants completed two types of cognitive tests and had their HbA1c levels (a measure of blood sugar and control) assessed.
At the study s onset, those with diabetes had already scored significantly lower on their examinations of cognitive function, compared to non-diabetics even after age, race, sex, and education were taken into account. And after about nine years of follow-up, diabetics continued to demonstrate a greater decline in cognition than patients without the disease. Furthermore, the degree of cognitive decline was associated with the severity of diabetes: higher HbA1c levels were associated with lower mean cognitive scores. It s important to note, however, that the cognitive scores among those patients who developed diabetes during the course of the study did not statistically differ from the group without diabetes; yet this result may have been due to the small number of participants newly diagnosed with the disease.
The researchers suggest that because diabetes is associated with microvascular disease, kidney disease, depression, stroke, hypertension, hyperlipidemia, and cardiovascular disease, such factors may also accelerate the rate of cognitive decline. Thus, doctors should be more conscientious about evaluating and tracking cognitive function among diabetic patients.
Upon reading the study, ACSH's Dr. Gilbert Ross was pleased to observe that the research was based not on data-dredging, but was instead a prospective study. The theory that if you can better control diabetes, then you may possibly reduce the acceleration of cognitive decline is an important one, he says, and follow-ups to this latest study may help to strengthen this association.