INSULIN AND COGNITIVE FUNCTION IN AN ELDERLY POPULATION - THE ROTTERDAM STUDY

OBJECTIVE - To examine the association between insulin and cognitive f unction in the population-based Rotterdam Study. RESEARCH DESIGN AND M ETHODS - Serum insulin was measured 2 h after an oral glucose load, wh ile global cognitive function was assessed by the Mini Mental State Ex amination in 5,510 subjects, aged 55 years and over. RESULTS - An incr ease in postload insulin only in women was associated with a decrease in cognitive function (age-adjusted regression coefficient -0.10 per 5 0 mU/l insulin; 95% CI -0.16 to -0.04). The association between insuli n resistance, assessed by the ratio of postload insulin over glucose, and cognitive function was not statistically significant. Further adju stment for the individual risk factors of serum glucose, BMI, HDL, sys tolic blood pressure, smoking, or use of estrogen did not change the r esults. The association was present in women with and without cardiova scular disease and present after excluding subjects with diabetes. Wom en with dementia, the extreme of cognitive dysfunction, had increased age-adjusted insulin levels (76.3 +/- 4.9 vs. 66.8 +/- 1.0 mU/l [means +/- SE], P = 0.06). CONCLUSIONS - The results of this study suggest t hat increased serum insulin may be associated with decreased cognitive function and dementia in women. These findings are more compatible wi th a direct effect of insulin on the brain than with an effect through an increase in cardiovascular risk factors.