Insulin and cognitive function in an elderly population. The Rotterdam Study.
OBJECTIVE
To examine the association between insulin and cognitive function in the population-based Rotterdam Study.


METHODS
Serum insulin was measured 2 h after an oral glucose load, while global cognitive function was assessed by the Mini Mental State Examination in 5,510 subjects, aged 55 years and over.


RESULTS
An increase in postload insulin only in women was associated with a decrease in cognitive function (age-adjusted regression coefficient -0.10 per 50 mU/l insulin; 95% CI -0.16 to -0.04). The association between insulin resistance, assessed by the ratio of postload insulin over glucose, and cognitive function was not statistically significant. Further adjustment for the individual risk factors of serum glucose, BMI, HDL, systolic blood pressure, smoking, or use of estrogen did not change the results. The association was present in women with and without cardiovascular disease and present after excluding subjects with diabetes. Women 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 that increased serum insulin may be associated with decreased cognitive function and dementia in women. These findings are more compatible with a direct effect of insulin on the brain than with an effect through an increase in cardiovascular risk factors.
Stolk
R P
RP
Department of Epidemiology and Biostatistics, Erasmus University Medical School, Rotterdam, The Netherlands. stolk@epib.fgg.eur.nl
Breteler
M M
MM
Ott
A
A
Pols
H A
HA
Lamberts
S W
SW
Grobbee
D E
DE
Hofman
A
A
D000368:Aged; D001786:Blood Glucose / Q000378:metabolism*; D001794:Blood Pressure; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology; D003071:Cognition; D003072:Cognition Disorders / Q000097:blood / Q000453:epidemiology; D015331:Cohort Studies; D003704:Dementia / Q000097:blood / Q000453:epidemiology; D015914:Estrogen Replacement Therapy / Q000706:statistics & numerical data; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D009426:Netherlands; D012044:Regression Analysis; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D013599:Systole
D001786:Blood Glucose; D007328:Insulin