Hyperinsulinemia and risk of Alzheimer disease.
OBJECTIVE
To explore the association between fasting insulin levels and dementia.


METHODS
Fasting insulin levels were measured from frozen sera using solid-phase chemiluminescent enzyme immunoassay in a sample of elderly subjects chosen at random from a cohort of persons aged 65 years and older from northern Manhattan. Dementia was diagnosed using standard methods. Neuropsychiatric testing was available on all subjects at each follow-up interval.


RESULTS
A total of 683 subjects without prevalent dementia were followed for 3,691 person-years and 149 persons developed dementia (137 Alzheimer disease [AD], 6 dementia associated with stroke, 6 other). The risk of AD doubled in the 39% of the sample with hyperinsulinemia (HR = 2.1; 95% CI: 1.5, 2.9) and was highest in people without diabetes. The HR relating presence of hyperinsulinemia or diabetes in 50% of our sample to AD was 2.2 (95% CI: 1.5, 3.1). The risk of AD attributable to the presence of hyperinsulinemia or diabetes was 39%. The HR of AD for the highest quartile of insulin compared to the lowest was 1.7 (95% CI: 1.0, 2.7; p for trend = 0.009). Hyperinsulinemia was also related to a significant decline in memory-related cognitive scores, but not to decline in other cognitive domains.


CONCLUSIONS
Hyperinsulinemia is associated with a higher risk of AD and decline in memory.
Luchsinger
Jose A
JA
Taub Institute for Research of Alzheimer's Disease and the Aging Brain, Joseph P. Mailman School of Public Health, Columbia University, New York, USA.
Tang
Ming-Xin
MX
Shea
Steven
S
Mayeux
Richard
R
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood* / Q000208:ethnology / Q000209:etiology; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000097:blood; D003071:Cognition; D003430:Cross-Sectional Studies; D003704:Dementia / Q000097:blood / Q000209:etiology; D003920:Diabetes Mellitus / Q000523:psychology; D005260:Female; D006801:Humans; D006946:Hyperinsulinism / Q000523:psychology*; D008137:Longitudinal Studies; D008297:Male; D016017:Odds Ratio; D015995:Prevalence; D016016:Proportional Hazards Models; D012307:Risk Factors; D020521:Stroke / Q000150:complications
D053327:Apolipoprotein E4; D001057:Apolipoproteins E