Compared with WT mice, the latency to enter the dark chamber was much shorter in saline-treated Ts65Dn mice, indicating cognitive impairment (WT+saline vs Ts65Dn+saline: p = 0.0033; WT+GLP-1 (9-36) vs Ts65Dn+saline: p = 0.0007; Fig. 5D). The gene discussed is GCG; the disease is Cognitive impairment.