MAPT and Zinc deficiency: Given the suspected link between zinc deficiency and AD, lower brain levels of zinc could underlie the specific reduction in Shank3a observed here (Baum et al., 2010; Grabrucker, 2014; Kim et al., 2021; Rivers-Auty et al., 2021; Chen et al., 2023) and the effect of Shank3a deficiency on tau and Aβ could form an amplification loop in AD.