IRS1 and Insulin resistance: Markers of insulin resistance were also reported in the hypothalamus of APP/PS1 mice [67] since the IRS-1 phosphorylated in serine 616 in the hippocampus at nine months of age was higher than that of the control group [68], and increased levels of IRS-1 phosphorylated in serine 636 and 312 in the frontal cortex at 13 months [69] were also demonstrated.