Diabetes and cognitive function in a middle-aged cohort: findings from the Whitehall II study.

OBJECTIVE

To compare cognitive performance in those with diabetes, impaired glucose tolerance, and normoglycemia in a middle-aged cohort.

METHODS

The authors analyzed data from a prospective occupational cohort study begun in 1985-1988 (baseline). Diabetes was classified from oral glucose tolerance tests that were performed in 1992-1993 (phase 3) and 1997-1999 (phase 5) and self reported diagnosis of diabetes from questionnaire at baseline, 1989 (phase 2), phase 3, 1995 (phase 4), and phase 5 of the study. A battery of cognitive tests (memory, Alice Heim 4 [AH 4], Mill Hill vocabulary test, phonemic fluency, and categorical fluency) were measured at phase 5 in 4,020 men and 1,627 women with a mean age of 56 and free of symptoms of stroke.

RESULTS

At phase 5, a total of 208 (5%) men and 101 (6%) women had diabetes while 405 (10%) men and 192 (12%) women had impaired glucose tolerance. Those with diabetes were at increased risk of poor performance in AH 4 compared to those without (men: OR, 2.45; 95% CI, 1.77 to 3.38; women: OR, 1.83; 95% CI, 1.09 to 3.08). These effects were independent of age, social position, vascular problems, and health-related behaviors. Impaired glucose tolerance was not related to any measure of cognition.

CONCLUSIONS

Type 2 diabetes is associated with poor performance in some aspects of cognition in middle-aged men and women.