IGHE and Alzheimer disease: Likewise, according to a more recent study, serum β-endorphin concentration was not only elevated in AD patients (ca. 12 pg/mL, i.e., ~3.46 pM vs. ca. 6 pg/mL, i.e., ~1.73 pM), but, alongside with trans-epidermal water loss and serum IgE level, it was suggested being used as independent biological marker for the disease severity and itch in AD [140].