It has been shown that impairment in either insulin or insulin-like growth factor (IGF)-1 signalling pathways can accelerate the progression of neurodegenerative disorders such as AD [11] and decreased permeation of peripheral insulin across the blood-brain barrier (BBB), leading to a shift in the proportion of brain to peripheral insulin levels [3, 6, 9]. The gene discussed is IGF1; the disease is Alzheimer disease.