ACTA1 and Alzheimer disease: Similar to the findings of Perry et al. [49], the α-SMA fraction of AD CAA− and CAA+ small and medium-sized arteries was significantly and equally decreased compared to that of NDCTRL small arteries and medium-sized arteries (~35–50 % decrease, p < 0.01; Fig. 2c, left), suggestive of a CAA-independent decrease in the arterial α-SMA fraction in the AD subjects.