IRS1 and Insulin resistance: Indeed, markers of insulin resistance, such as increased quantities of Ser-phosphorylated and inhibited IRS-1 downstream of the IR, have been identified in the hippocampus and cortex of AD patients, correlating with plaque deposition, disease progression and memory decline (Steen et al., 2005; Moloney et al., 2010; Talbot et al., 2012).