ARNT and Alzheimer disease: While rapid-metabolizing AHR ligands that activate the AHR/ARNT/FLG axis may be beneficial in treating AD, other slow-metabolizing dioxins and environmental pollutants cause potent and long-lasting activation of the AHR axis, which exacerbates barrier dysfunction and aggravates AD, likely due to an abnormally accelerated keratinization process, epidermal acanthosis, the elongation of nerve fibers, and the production of pruritogenic artemin [169].