The most robust loss of GAD67 immunoreactive neurons occurred in the hilus of TgF344-AD rats compared to age-matched NTg rats (genotype: P < 0.0001; age: P = 0.07; interaction: P = 0.04), with a significant decrease at 9 and 15 months of age (P < 0.0001 and P = 0.002, respectively), whereas no difference was detected at 12 months of age (P = 0.29; Fig. 2f; Table 2). Here, GAD1 is linked to Alzheimer disease.