AHR and Alzheimer disease: Malassezia yeasts, commensal cutaneous micro-organisms, are implicated in the pathogenesis of some dermatological inflammatory diseases such as pityriasis versicolor (PV), seborrheic dermatitis (SD), or AD; interestingly, skin extracts from patients with these Malassezia-associated diseases demonstrated a 10–1000-fold higher AhR-activating ability than control skin extracts.