Figure 5. Principal Component Analysis on middle-aged animals. (A) Variable factor map. Fasting blood glucose was considered as the qualitative variable on age, body mass (BM), number of errors (errors), volumes of hippocampus (Hipp Vol), septum (Sept Vol) and caudate nucleus (Caud Vol), insulin (Ins) and glucose tolerance index (OGTT-AUC) (B) Individual dispersion of PCA: x-axis: principal component 1 (PC1: 34.3%), y axis: principal component 2 (PC2: 17.8%). A threshold of 4 mmol/L defined normal blood glucose (fasting glucose less than 4 mmol/L, blue) and high blood glucose (fasting glucose more than 4 mmol/L, red).