The following three distinctive approaches can preliminarily verify this putative model: (1) observing AD development in different T-cell-deficient murine models; (2) applying anti-PD-1 or anti-PD-L1 monoclonal antibodies in AD patients and correlating PD-1/PD-L1 blockade with damaged brain repair; and (3) observing whether the regulation of T-cell activity can alter the rate of deterioration and cognitive impairment. The gene discussed is CD274; the disease is Cognitive impairment.