Development of vascular risk factors over 15 years in relation to cognition: the Hoorn Study.

OBJECTIVES

To investigate the development of vascular risk factor levels at four points over 15 years in relation to late-life cognitive functioning.

DESIGN

Longitudinal population-based study.

SETTING

The Hoorn Study, a community-based cohort study of glucose metabolism and cardiovascular risk.

PARTICIPANTS

Three hundred eighty individuals without dementia (mean baseline age 57.7 ± 5.5).

MEASUREMENTS

Four extensive medical examinations were conducted over 15 years. Cognition was assessed in detail at the fourth examination. The time course of vascular risk factors across the examinations was compared between individuals in the highest tertile (good performance) and those in the lowest tertile (poor performance) of cognitive functioning on three cognitive domains (memory, information processing speed, and attention and executive functioning (A&EF)).

RESULTS

Individuals with poor information processing speed had higher levels of systolic blood pressure at baseline (mean difference (standard error) 11.6 (2.6) mmHg, P < .001) than those with good information processing speed. Individuals with poor A&EF had a higher waist:hip ratio (3.03 (1.15), P = .009), glycosylated hemoglobin (0.29% (0.10%), P = .005) and total cholesterol:high-density lipoprotein cholesterol ratio (0.38 (0.19), P = .04) at baseline than individuals with good A&EF, although the differences in vascular risk factor levels between the poor and good cognition group diminished with increasing age.

CONCLUSION

High blood pressure, adiposity, hypercholesterolemia, and hyperglycemia at midlife are associated with late-life cognitive dysfunction, but for most risk factors, this relationship gradually attenuates with increasing age. These results suggest that timing of vascular treatment strategies to prevent cognitive impairment is critical.