Atrophy patterns in cerebral amyloid angiopathy with and without cortical superficial siderosis

Objective To investigate differential atrophy patterns based on the presence of cortical superficial siderosis (cSS) and the role of cSS in predicting amyloid positivity in memory clinic patients fulfilling the diagnostic criteria for probable cerebral amyloid angiopathy (CAA).MethodsWe retrospectively collected data from 44 cognitively impaired patients with probable CAA who underwent 3-dimensional, T1-weighted MRIs (cSS+, n = 27; cSS-, n = 17). Amyloid-positive patients with Alzheimer disease (AD) (n = 56) and amyloid-negative cognitively normal participants (n = 34) were recruited as controls. Among the patients with CAA who underwent amyloid-PET scans (75.0%), we investigated whether amyloid-negative cases were unevenly distributed based on cSS presentation. APOE genotypes, Mini-Mental State Examination scores, and cortical atrophy pattern along with hippocampal volume were compared across groups.ResultsTen patients with probable CAA presented amyloid negativity and all of them belonged to the cSS-group (58.8%). Compared to the cSS-group, the cSS+ group presented higher APOE ϵ4 frequency, worse memory dysfunction, and lower hippocampal volume. Compared with cognitively normal participants, the cSS+ group exhibited atrophy in the precuneus, posterior cingulate, parietotemporal, superior frontal, and medial temporal areas, a pattern similar to AD-specific atrophy. The cSS-group exhibited atrophy in the parietotemporal, superior frontal, and precentral regions.ConclusionOur findings imply that the current version of the Boston criteria may not be sufficient enough to remove non-CAA cases from a cognitively impaired population, especially in the absence of cSS. Patients with probable CAA presenting cSS appear to reflect a CAA phenotype that shares pathologic hallmarks with AD, providing insight into the CAA-to-AD continuum.