IL4 and Alzheimer disease: At the same time, Th2-associated cytokines (IL-4, IL-13) also showed increased levels (39), and these cytokines may further promote T-cell infiltration into the skin and hair follicles, thereby triggering inflammatory responses and follicular damage (33, 40), and in the group of patients with AA combined with AD, the infiltration of Th2 cells around the diseased follicles was more prevalent.