It is thought that tau may be in a feedback loop with Aβ in AD, where an increase in Aβ accumulation increases NFT formation of tau, which further stimulates Aβ aggregation.108, 109 Therefore, understanding the mechanism(s) by which Aβ accumulation elicits a tauopathy is crucial in defining how AD manifests itself, and it is no surprise that a complete description of Hsp90’s role in tau phosphorylation is therefore essential. This evidence concerns the gene HSP90AA1 and Alzheimer disease.