Abstract WP070: Cognitive Susceptibility to Intracranial Large Artery Enlargement Across Cerebral Small Vessel Disease Subtypes

Background: Brain large artery (LA) dilatation, such as in the basilar or internal carotid artery (BA/ICA), has been linked to dementia risk partly due to changes in brain hemodynamics. Small vessel disease (SVD) is also a contributor to poorer cognition and dementia but the relationship between LA dilatation and SVD on cognition is unclear. We investigated whether the association between LA diameter and cognition differs by SVD presence and subtype. Methods: We analyzed data from a community-based cohort of adults ≥ 50 years without dementia. All participants underwent 3T brain MRI including TOF-MRA. SVD markers-white matter hyperintensities (WMH), lacune, and cerebral microbleed (CMB)-were assessed to classify individuals into four groups: no CSVD, ischemic SVD (WMH ± lacune), mixed CMB, and strictly lobar CMB. Diameters of ICA and BA were measured automatically using LAVA software under a standardized protocol. Cognitive function was tested across memory, language, executive, and visuospatial domains. Multivariable linear regression adjusted for age, sex, and education assessed associations between LA diameters and cognition. A Bonferroni-corrected p-value <0.002 accounted for multiple comparisons. Results: A total of 216 patients (age: 71±59 years; 68% female) were included: 104 no SVD, 50 ischemic SVD, 34 mixed CMB and 27 strictly lobar CMB. Demographics were similar across groups, except ischemic SVD group was older and strictly lobar CMB group had lower blood pressure. To account for brain size, arterial diameters were normalized by intracranial volume. Multivariable linear regression revealed no association between LA diameter and cognitive functions in participants without SVD. Among SVD groups, only within the ischemic SVD, larger ICA diameters were significantly associated with worse visuospatial function measured by the Clock Drawing Test (left ICA: β =–0.49 per 1 mm -2 increase, P=0.001; right ICA: β =–0.50 per 1 mm -2 increase, P=0.001). BA diameter was not related to any cognitive outcome in any group. Conclusions: In asymptomatic older adults, intracranial carotid artery dilatation was linked to cognitive impairment, particularly in visuospatial function, only in the presence of ischemic SVD. We provide novel insights into how brain arterial dilatation might relate to cognition depending on pre-existing SVD. Further studies are needed to assess if prospectively, cognitive trajectories are worse among those with brain arterial dilatation and SVD.