FLG and Alzheimer disease: The majority of AD patients have skin barrier dysfunction either due to mutations in genes such as filaggrin and tight junctions or from a more generalized disruption from the presence of Th2 cytokines (Palmer et al., 2006; Sandilands et al., 2009; Jungersted et al., 2010; Rerknimitr et al., 2017; Drislane and Irvine, 2020).