We created a semiquantitative summary of cerebral amyloid angiopathy (CAA) pathology in 4 neocortical regions: midfrontal, midtemporal, parietal, and calcarine cortices. Paraffin-embedded sections were immunostained for beta-amyloid using 1 of 3 monoclonal anti-human antibodies: 4G8 (1:9000; Covance Labs, Madison, WI), 6F/3D (1:50; Dako North America Inc., Carpinteria, CA), and 10D5 (1:600; Elan Pharmaceuticals, San Francisco, CA).

CAA assessment was similar to a recently proposed protocol (Love et al., 2014): for each region, meningeal and parenchymal vessels were assessed for amyloid deposition and scored from 0 to 4, where: 0=no deposition 1=scattered segmental but no circumferential deposition 2=circumferential deposition up to 10 vessels 3=circumferential deposition up to 75% of the region 4=circumferential deposition over 75% of the total region. CAA score for each region was the maximum of the meningeal and parenchymal CAA scores. Scores were averaged across regions and summarized as a continuous measure of CAA pathology.

For the semiquantitative summary, we classified CAA scores into a 4-level severity rating using cutoffs determined by the neuropathologist: