The roles of insulin in the mammalian brain are considered as follows [94]: (1) proteostasis influencing clearance of the amyloid β peptide and phosphorylation of tau, which are hallmarks of Alzheimer’s disease, and (2) modulation of vascular function through the effects on vasoreactivity, lipid metabolism, and inflammation. The gene discussed is INS; the disease is early-onset autosomal dominant Alzheimer disease.