At the beginning of the study and again
every 18 months through 2003, each
participant underwent an in-person interview
and standard assessment, which included a
medical history, physical and neurological
examination, and a battery of neurological
tests that measured learning, memory, reason
and language skills, among others.
Of the participants, 23.9 percent had
diabetes, 68.2 percent had hypertension,
33.9 percent had heart disease and 15
percent had had a stroke.
During an average of 6.1 years of follow-up,
334 individuals developed mild cognitive
impairment, including 160 amnestic cases and
174 non-amnestic cases.
Diabetes was related to a significantly
higher risk of mild cognitive impairment
overall and of amnestic mild cognitive
impairment specifically after controlling
for other factors that may affect risk,
including age, ethnic group, years of
education and heart and blood vessel
disease.
"The risk of mild cognitive impairment
attributable to diabetes was 8.8 percent for
the whole sample, 8.4 percent for
African-American persons, 11 percent for
Hispanic persons and 4.6 percent for
non-Hispanic white persons, reflecting the
differences in diabetes prevalence by ethnic
group," the authors write.
Diabetes could be related to a higher risk
for amnestic mild cognitive impairment by
directly affecting the build-up of plaques
in the brain, a hallmark characteristic of
Alzheimer's disease, the authors note.
In addition, cerebrovascular
disease-diseases such as stroke that affect
the vessels supplying blood to the brain-is
related to both diabetes and Alzheimer's
disease.
"Our results provide further support to the
potentially important independent role of
diabetes in the pathogenesis of Alzheimer's
disease," the authors conclude.
"Diabetes may also be a risk factor for non-amnestic
forms of mild cognitive impairment and
cognitive impairment, but our analyses need
to be repeated in a larger sample."
