IL17A and Alzheimer disease: Phototherapy and systemic immunosuppressants (Omazumab IGE inhibitors, Fezakinumab unzanumab IL-22 inhibitors, Suchizumab IL-17A inhibitors, and Nemolizumab IL-31 inhibitors) are used for refractory and severe AD by improving skin hydration and repairing skin barrier function, and the above agents target different pathways in the immune system (JAK-STAT, phosphodiesterase 4, AhR receptor, and Th2 cytokines).