Ethnic differences in the cerebrovascular impact of hypertension

Small-vessel cerebrovascular disease and vascular cognitive impairment are more prevalent in hypertensive subjects of black African origin compared with Caucasians, but the relationships between blood pressure (BP), regional white matter damage and neuropsychological function have not been studied in well-characterised samples of subjects belonging to different ethnicities.

Twenty-four-hour ambulatory BP, brain white matter lesion volumes on magnetic resonance imaging and executive cognitive function were compared in 41 Caucasian and 47 African-Caribbean subjects on optimal treatment attending a hypertension clinic.

African-Caribbean subjects were 4 years younger but had been hypertensive for 3 years longer than Caucasians. Their mean 24-hour systolic (136.6 vs. 129.4 mm Hg, p = 0.011) and diastolic (77.8 vs. 72.6 mm Hg, p = 0.006) BP were also higher despite being well-controlled. In multivariate models, African-Caribbean subjects had a greater parieto-occipital white matter lesion volume [adjusted difference: 319 mm(3) (95% CI: 62-575), p = 0.016] and poorer performance on executive function [time difference: 0.375 s (95% CI: 0.191-0.558), p = 0.0001] and verbal fluency [score difference: -6.863 (95% CI: -12.531 to -1.195), p = 0.018] tests after adjusting for covariance in age, gender, vascular risk profile, duration of hypertension and education, and premorbid intelligence.

African-Caribbean ethnicity was independently related to increased hypertensive white matter damage and executive cognitive dysfunction, the reasons for which merit further investigation.