Racial Differences in Prevalence and Risk for Intracranial Atherosclerosis in a US Community-Based Population.

Importance: Intracranial atherosclerotic disease (ICAD) is an important cause of stroke; however, little is known about racial differences in ICAD prevalence and its risk factors.

Objective: To determine racial differences in ICAD prevalence and the risk factors (both midlife and concurrent) associated with its development in a large, US community-based cohort.

Design, Setting, and Participants: Analysis of 1752 black and white participants recruited from the Atherosclerosis Risk in Communities (ARIC) cohort study who underwent 3-dimensional intracranial vessel wall magnetic resonance imaging from October 18, 2011 to December 30, 2013; data analysis was performed from October 18, 2011 to May 13, 2015.

Exposures: Midlife and concurrent cardiovascular risk factors.

Main Outcomes and Measures: Intracranial plaque presence, size (maximum normalized wall index) and number were assessed by vessel wall magnetic resonance imaging. Midlife and concurrent vascular risk factor associations were determined by Poisson regression (plaque presence), negative binominal regression (plaque number), and linear regression (plaque size), and compared between races.

Results: Of the 1752 study participants (mean [SD] age, 77.6 [5.3] years; range, 67-90 years), 1023 (58.4%) were women and 518 (29.6%) were black. Black men had the highest prevalence (50.9% vs 35.9% for black women, 35.5% for white men, and 30.2% for white women; P 

Conclusions and Relevance: The prevalence of ICAD was highest in black men. Midlife smoking and diabetes were strongly associated with late-life ICAD in blacks only, whereas midlife hypertension and hyperlipidemia were associated with late-life ICAD in both races. These associations may help to explain racial differences in US stroke rates and offer insight into preventive risk-factor management strategies.