Association of Obesity With Intracranial Hemodynamic Alterations

BACKGROUND: Obesity increases the risk of stroke and cognitive decline, but its association with intracranial arterial hemodynamics remains unclear. We examined whether obesity score is associated with intracranial signal-intensity gradient, a time-of-flight magnetic resonance angiography–derived surrogate of arterial wall shear conditions, and whether this association differs by vascular territory. METHODS: This cross-sectional study included 5618 adults who underwent comprehensive health screening, including intracranial time-of-flight magnetic resonance angiography, in the Republic of Korea between 2012 and 2020. Body mass index was calculated from measured height and weight, and waist circumference was measured by health-screening staff on the same day as brain magnetic resonance angiography. An obesity score was calculated by assigning 1 point each for general and abdominal obesity, yielding scores of 0 (neither), 1 (either), or 2 (both). Arterial SIG and arterial radius were calculated using semiautomated 3-dimensional vessel segmentation. Lower SIG values were interpreted as reflecting reduced arterial wall shear conditions. Multivariable linear regression models assessed the association between obesity score and SIG across 11 intracranial arteries, adjusting for demographics, arterial radius, and cardiometabolic factors. RESULTS: Among 5618 participants (mean [SD] age, 55.9 [8.6] years; 45.2% women), higher obesity score was associated with lower SIG across all intracranial arteries ( P value for trend <0.001). In adjusted models, each 1-point increase in obesity score was associated with reduced SIG, including in the basilar artery (B=−0.26 [95% CI, −0.31 to −0.21]). The obesity-related reduction in SIG was greater in the posterior than anterior circulation and persisted after adjustment for arterial radius and cardiometabolic factors. CONCLUSIONS: A higher obesity score was associated with reduced intracranial arterial SIG, consistent with adverse time-of-flight magnetic resonance angiography–derived flow-related hemodynamic alterations. Greater reductions in the posterior circulation suggest territory-specific vulnerability, which may be associated with early cerebrovascular compromise in the context of obesity.