Importantly, our findings largely replicated genotype-related neurochemical changes and a shift of arginine metabolism towards the arginase-polyamine pathway [28], further demonstrating the upregulation of the L-citrulline recycling, arginase-ODC and polyamine retro-conversion pathways (Figure 1), the association between altered polyamines (putrescine and spermidine) and the reduced anxiety and hyperactivity behaviours observed in PS19 mice at 8 months. Here, ODC1 is linked to Anxiety.