Abstract 131: Brain Mri Biomarkers Of Impaired Balance And Slow Walk Speed: Atherosclerosis Risk In Communities And UK Biobank Studies

Abstract

Background and Objectives: Vascular brain injury (VBI) may contribute to imbalance and slow walk speed, but this is uncertain. We hypothesize that MRI biomarkers of VBI associate with impaired balance and slow walk speed. Methods: We performed separate, cross-sectional analyses in the Atherosclerosis Risk in Communities (ARIC) and UK Biobank (UKB) studies. Eligible participants had no prior clinical stroke and underwent a brain MRI and balance and walk speed ascertainment. MRI biomarkers of VBI analyzed were: ventricular volume, white matter hyperintensity volume (WMH), non-lacunar infarction, lacunar infarction, microhemorrhage in ARIC; ventricular volume, brain volume, WMH, fractional anisotropy (FA), mean diffusivity (MD), intra-cellular volume fraction, isotropic free water volume fraction in UKB. Quantitative biomarker levels were classified into tertiles, the unhealthiest tertile designated as the exposure. Our outcomes were poor balance and slow walk speed. We constructed multivariable logistic regression models to examine the associations between each MRI biomarker and the outcomes, adjusting for demographics and clinical history. Results: We included 1,626 ARIC participants (mean age 76.2 years; 23.4% impaired balance, 25.0% slow walk speed) and 40,098 UKB participants (mean age 55 years; 15.8% impaired balance, 2.8% slow walk speed). In ARIC, impaired balance was associated with 4 of 5 MRI measures of VBI in adjusted analysis (all p-values <0.05). The strongest association was with WMH (OR 1.36; 95% C.I. 1.04-1.76). Slow walk speed in ARIC was significantly associated with 4 of 5 MRI measures; the strongest association was with silent lacunar infarcts (OR 2.17; 95% C.I. 1.61-2.93). In UKB, poor balance was associated with all MRI biomarkers except WMH. The strongest association was with FA (OR 1.16; 95% C.I. 1.08-1.24). Slow walking speed was associated with WMH, FA, and MD. The strongest association was with FA (OR 1.42; 95% C.I. 1.21-1.67). Conclusions: We demonstrate that MRI measures of VBI are independently associated with impaired balance and slow walk speed in two studies of community-dwelling adults with no history of clinical stroke. Consequences of VBI may extend beyond clinically apparent stroke to also include mobility.