FLG and Alzheimer disease: Even though the exact pathogenesis of AD is not completely understood, it is assumed to be a combination of (epi)genetic (e.g., filaggrin mutations), immunologic (inflammation with a TH2-shift and higher IgE-levels), and exogenous factors, such as exposure to allergens and irritants, infections and alteration in the physiological skin microbiome, excessive hygiene, and climatic changes [5,7,8,9,10,11,12,13].