Type 2 diabetes and cognitive decline over 14 years in middle-aged African Americans and whites: the ARIC Brain MRI Study.
BACKGROUND
Diabetes predicts late-life dementia, but the association with rate of cognitive decline is inconsistent and has rarely been examined in non-white populations, despite the high prevalence of diabetes in African Americans. We evaluated the effect of diabetes on cognitive decline in middle-aged African Americans and whites.


METHODS
Atherosclerosis Risk in Communities (ARIC) Brain MRI Study participants (n = 1,886, mean age = 60, 49% African American) underwent assessments of verbal memory, processing speed, and verbal fluency four times over 14 years. Using race-stratified mixed linear effects models, we examined cognitive change for participants with prevalent (baseline) diabetes and incident (diagnosed after baseline) diabetes versus those without diabetes.


RESULTS
African Americans had more advanced diabetes, as indicated by fasting blood glucose levels, anti-diabetes medication use, and cardiovascular risk profiles. African Americans with prevalent diabetes experienced 41% greater annual decline in processing speed scores (p = 0.048) and 50% greater annual decline in verbal fluency scores (p = 0.042) than those without diabetes; incident diabetes was not associated with cognitive decline. Among whites, diabetes was not associated with cognitive decline.


CONCLUSIONS
Prevalent diabetes was associated with greater cognitive decline in middle-aged African Americans, possibly reflecting adverse effects of longer duration and more advanced diabetes.
Department of Epidemiology and Biostatistics, University of California, San Francisco, Calif., USA.
Elizabeth R
ER
Mayeda
Mary N
MN
Haan
John
J
Neuhaus
Kristine
K
Yaffe
David S
DS
Knopman
A Richey
AR
Sharrett
Michael E
ME
Griswold
Thomas H
TH
Mosley
D001741:Black or African American; D000368:Aged; D003072:Cognition Disorders / Q000150:complications* / Q000208:ethnology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000208:ethnology / Q000523:psychology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D015995:Prevalence; D012307:Risk Factors; D044465:White People