Midlife stroke risk and cognitive decline: a 10-year follow-up of the Whitehall II cohort study.

BACKGROUND

Stroke is associated with an increased risk of dementia. However, it is unclear whether risk of stroke in those free of stroke, particularly in nonelderly populations, leads to differential rates of cognitive decline. Our aim was to assess whether risk of stroke in mid life is associated with cognitive decline over 10 years of follow-up.

METHODS

We studied 4153 men and 1657 women (mean age, 55.6 years at baseline) from the Whitehall II study, a longitudinal British cohort study. We used the Framingham Stroke Risk Profile (FSRP), which incorporates age, sex, systolic blood pressure, diabetes mellitus, smoking, prior cardiovascular disease, atrial fibrillation, left ventricular hypertrophy, and use of antihypertensive medication. Cognitive tests included reasoning, memory, verbal fluency, and vocabulary assessed three times over 10 years. Longitudinal associations between FSRP and its components were tested using mixed-effects models, and rates of cognitive change over 10 years were estimated.

RESULTS

Higher stroke risk was associated with faster decline in verbal fluency, vocabulary, and global cognition. For example, for global cognition there was a greater decline in the highest FSRP quartile (-0.25 of a standard deviation; 95% confidence interval: -0.28 to -0.21) compared with the lowest risk quartile (P = .03). No association was observed for memory and reasoning. Of the individual components of FSRP, only diabetes mellitus was associated independently with faster cognitive decline (β = -0.06; 95% confidence interval, -0.01 to 0.003; P = .03).

CONCLUSION

Elevated stroke risk at midlife is associated with accelerated cognitive decline over 10 years. Aggregation of risk factors may be especially important in this association.