JAK1 and Alzheimer disease: Baricitinib, a selective JAK1/JAK2 inhibitor, is approved in several countries for the treatment of moderate-to-severe AD and is recommended in adults who are candidates for systemic therapy.7 It is also approved for the treatment of moderate-to-severe rheumatoid arthritis in adults in Europe, Japan, and the United States, and for the treatment of severe alopecia areata in Japan and the United States.