The complex expression patterns and activity of the different PDEs throughout the CNS under normal and pathological conditions have been the subject of intense interest during the past decade, especially in regard to the therapeutic potential of PDE inhibitors for CNS disorders.22,23 We found that PDE IIIA expression in the microvessels, predominantly in the smooth muscle cell layers, was markedly upregulated as CAA severity increased. This evidence concerns the gene ALDH7A1 and central nervous system disorder.