Immune modulation in animal models of AD and dementia achieved through treatment with anti-PD-1 or anti–PD-L1 antibodies approaches, resulted in disease modification, manifested by milder pathology paralleled by cognitive improvement (Baruch et al., 2016; Rosenzweig et al., 2019; Castellani and Schwartz, 2020). This evidence concerns the gene PDCD1 and Alzheimer disease.