FLG and Alzheimer disease: AD is a pruritic skin disease that develops and progresses in association with a variety of factors, such as dry skin and epidermal barrier dysfunction due to genetic abnormalities (e.g., filaggrin gene mutations) or non-hereditary chronic inflammation [2,3,4,5], innate immunity dysregulation [6,7], dominance of T helper (Th) 2 cytokine (i.e., interleukin [IL]-4 and IL-13) immunity [2,8,9,10], and intractable and diverse itching [11,12,13].