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Newsletter >
Diabetes and Cognition
August 13, 2008
Individuals with mild cognitive impairment appear more
likely to have earlier onset, longer duration and greater
severity of diabetes, according to a report in the August
issue of Archives of Neurology, one of the JAMA/Archives
journals.
Mild cognitive impairment is a transitional stage between
normal aging and dementia, according to background
information in the article. Previous studies have found an
association between mild cognitive impairment and diabetes.
Poor blood glucose control over time may lead to neuron
loss, and diabetes is associated with cardiovascular
disease risk and stroke, which also may increase the risk
of cognitive impairment.
Rosebud O. Roberts, M.B.Ch.B., M.S., and colleagues at Mayo
Clinic, Rochester, Minn., studied individuals from Olmsted
County, Minnesota, who were age 70 to 89 on Oct. 1, 2004.
Participants received a neurological examination,
neuropsychological evaluation and tests of blood glucose
levels, and completed an interview with questions about
diabetes history, treatment and complications. A medical
records linkage system was used to confirm diabetes
history.
Rates of diabetes were similar among 329 individuals with
mild cognitive impairment (20.1 percent) and 1,640
participants without mild cognitive impairment (17.7
percent). However, mild cognitive impairment was associated
with developing diabetes before age 65, having diabetes for
10 years or longer, being treated with insulin and having
diabetes complications.
“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,” the authors write.
That individuals with the eye disease diabetic retinopathy
were twice as likely to have mild cognitive impairment
supports the theory that diabetes-related damage to blood
vessels in the brain may contribute to the development of
cognitive problems.
“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 conclude.
“In contrast, late onset of diabetes mellitus, short
duration of diabetes mellitus or well-controlled diabetes
mellitus may have a lesser effect.”
Arch Neurol. 2008;65[8]:1066-1073.
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