Peripheral blood CD4+ lymphocyte frequencies were significantly decreased in 12- and 20-month groups compared to control mice (p=0.0124, p=0.0184, respectively), while CD8+ lymphocyte frequency significantly increased in 12- and 20-month APP/PS1 mice compared to non-Tg controls (p=0.0213, p=0.0069, respectively) (Figure 2B) suggesting an increased cytotoxic and pro-inflammatory environment throughout AD progression. The gene discussed is CD4; the disease is Alzheimer disease.