CD4 and Alzheimer disease: Enhancing meningeal lymphatic drainage can promote Aβ clearance and improve cognitive function in a mouse model.163 Changes in T cell senescence are also associated with cognitive decline.164 Compared with healthy young or elderly individuals, patients with AD exhibit an expansion of senescent T cells (within both the CD4+ and CD8+ populations) in the peripheral blood.165 CD4+ effector T cells in peripheral blood can differentiate into Th17 and Th1 subsets.