Carotid intima-media thickness and silent brain infarctions in a biracial cohort: The atherosclerosis risk in communities (ARIC) Study

BACKGROUND Both hypertensive and atherosclerotic processes contribute to common carotid artery intima-media thickness (CCA-IMT). Elevated CCA-IMT may be indicative of subclinical cerebrovascular disease; however, its role in the absence of concomitant carotid artery plaque is uncertain, and few studies have examined associations in Black populations. MATERIALS AND METHODS At cohort visit 3 (1993-1995) a subset of stroke-free participants (641 Blacks and 702 Whites, mean age 63) from the Atherosclerosis Risk in Communities (ARIC) study was imaged by brain MRI and carotid ultrasound. A CCA-IMT >0.9 mm was considered elevated. Asymptomatic brain lesions ≥3 mm were considered silent brain infarctions (SBI). Subcortical SBI measuring 3 to <20 mm were considered lacunes. Associations between elevated CCA-IMT and SBI were analyzed with Poisson regression. RESULTS Elevated CCA-IMT was identified in 168 participants (16% of Blacks, 10% of Whites), and SBI were observed in 156 (15% of Blacks, 8% of Whites). Elevated CCA-IMT was strongly related to anterior circulation SBI, posterior circulation SBI, and lacunes. After adjustments, elevated CCA-IMT remained associated with greater number of lacunes in Blacks ([prevalence ratio, PR] = 1.60; 95% confidence interval [CI]: 1.02-2.51), but not Whites (PR = 0.85; 95% CI: 0.35-2.04); P value for interaction = 0.12. Among Black participants without concomitant carotid plaque, elevated CCA-IMT was associated with twice the number of lacunes (PR = 2.00; 95% CI: 1.05-3.82). CONCLUSIONS In older Black adults, elevated CCA-IMT is independently associated with lipohyalinosis of the cerebral small vessels, irrespective of concomitant carotid plaque and vascular risk factors.