Background/Purpose: Cerebral Amyloid Angiopathy (CAA) leads to leukoaraiosis, lacunar infarcts and cortical tissue loss. We hypothesized that CAA is also associated with white matter atrophy (WMA).
Methods: We have compared volumetric multimodal MRIs from 72 prospectively enrolled non-demented patients with probable CAA (per Boston criteria), to 3 other well-studied cohorts: 289 Healthy Controls (HC) from the Harvard Aging Brain (HAB) study, 231 HC and 198 patients with AD from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Validated FreeSurfer algorithms were used to calculate White Matter Volume (WMV), white matter hyperintensity volume (WMHv), and cortical thickness. Microbleeds (MBs) were counted on SWI-MRI. Measures were obtained from the contralateral hemisphere if intracerebral hemorrhage present. All volumes were corrected for total intracranial volume (ICV), so reported as percent of ICV.
Results: The CAA patients were significantly younger (mean age: 70.1) compared to both HC cohorts (ADNI-HC: 76.0, p<0.001, HAB-HC: 73.8, p < 0.001), and to patients with AD (75.5, p < 0.001). Despite being younger, patients with CAA presented significantly lower global WMV (28% ± 2.6) than both ADNI-HC (29.2% ± 2.2, p < 0.001), HAB-HC (29.0% ± 2.5, p = 0.001), and patients with AD (28.7% ± 2.2, p = 0.02) [Figure]. The association persisted after correcting for age, gender and WMHv. Within the CAA cohort, there was a negative correlation between WMV and lobar MB counts (rho = -0.26, p = 0.03), it remained significant after correcting for age, gender, WMHv (p=0.016). There were no significant associations however between WMV and neither WMHv, nor cortical thickness (both p>0.2).
Conclusions: Patients with CAA show WMA when compared to older HC and AD. WMA independently correlates with MBs, a marker of CAA severity. Consistent spatial patterns of atrophy especially in posterior regions when compared to both HC and AD [Figure] might represent the “WMA signature of CAA”.