INS and Alzheimer disease: Low VA nutritional status might impair the liver and pancreas to disrupt the insulin signaling pathway and glucose uptake and transport in the brain, and increase Aβ1-42/Aβ1-40 and p-tau/t-tau ratios, further promoting the senile plaque deposit and aggregating cerebral neuroinflammation, finally to exacerbate AD pathology and cause nesting behavior disorder.