Taxifolin (dihydroquercetin; Figure 1), a naturally occurring flavonoid polyphenolic compound, despite its limited blood–brain barrier, exhibited pleiotropic neuroprotective effects on cerebral amyloid angiopathy (CAA) in the mice models of AD through suppression of the amyloid-β formation, and through its anti-inflammatory effect, and thereby diminished production of the “triggering receptor expressed on myeloid cell 2” (TREM2) in the brain. This evidence concerns the gene TREM2 and Alzheimer disease.