Abstract WP344: Basal Ganglia Atrophy in Cerebral Amyloid Angiopathy

Abstract

Background/Purpose: Cerebral Amyloid Angiopathy (CAA) is associated with cortical and white matter atrophy. We hypothesized that atrophy in CAA extended into the subcortical gray matter as well and might explain previously observed alterations in subcortical gray matter diffusion-tensor properties. Methods: We compared multimodal MRIs from 80 prospectively enrolled non-demented patients with probable CAA, to two other cohorts: 80 Healthy Controls (HC) and 80 patients with Alzheimer’s Disease (AD) from the AD Neuroimaging Initiative. Validated FreeSurfer algorithms were used to calculate Gray Matter (GMV) and Basal Ganglia Volumes (BGV), expressed as percentage of intracranial volume (ICV). High-resolution diffusion scans were used to calculate the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) within the basal ganglia. A visual basal ganglia atrophy scale was also developed to compare atrophy between 93 patients with CAA-related intracerebral hemorrhage (CAA-ICH) and 93 age-matched patients diagnosed with Hypertensive Arteriopathy and ICH (HTN-ICH). Results: CAA patients (mean age: 70.3 ± 8.5) were age-matched to HC (71.8 ± 3.7) and AD patients (70.4 ± 6.8). Patients with CAA had significantly lower BGV (1.16% ± 0.14) when compared to both HC (1.30% ± 0.13, p<0.0001) and AD (1.23% ± 0.12, p=0.003). Within the CAA cohort, there was a positive association between BGV and GMV (r=0.45, p<0.0001) and negative association between BGV and FA (r=-0.36, p=0.001). All associations remained independent after correcting for age, sex, and presence of hypertension. For the clinical ICH cohorts, patients diagnosed with CAA-ICH displayed significantly lower visually rated BGV when compared to similar aged patients with HTN-ICH (mean age: 68.5 for both groups, basal ganglia atrophy scale: 7.31 ± 1.03 vs 8.24 ± 1.14, p<0.0001). Conclusions: Patients with CAA displayed substantial atrophy in the basal ganglia when compared to HC, AD, and HTN-ICH patients. Within the CAA cohort, greater basal ganglia atrophy was independently correlated with greater cortical atrophy and previously observed increases in basal ganglia anisotropy. The mechanisms for and clinical manifestations of CAA-related basal ganglia atrophy remain to be determined.