Upadacitinib is a selective JAK1 inhibitor, only approved in dermatology for AD, blocking signaling of T-helper 1 (TH1)- and TH2-associated cytokines.7 We decided on initiating a selective JAK1 biologic rather than a pan-JAK inhibitor to avoid reported adverse effects of JAK2 and JAK3 on haematopoiesis, thus reducing the side effect profile for the patients.9 CPD is a heterogenous disease with a poorly understood subtype cytokine profile. Here, JAK2 is linked to Alzheimer disease.