Obesity and Alzheimer's disease: a link between body weight and cognitive function in old age.

Obesity is now a global health hazard. It not only predisposes to an array of risk factors leading to increased morbidity and mortality amongst adults but it also has a major negative impact on children's health. The deleterious effects of obesity on cardiovascular system have now been well acknowledged. It causes insulin resistance that in turn leads to diabetes, hypertension and cardiovascular abnormalities. The vascular effects of obesity may have a role in the development of a rapidly growing disease of late life, Alzheimer's disease. The precise mechanisms of the association between adiposity and impairment of cognitive performance remain to be elucidated. However, negative impact of obesity on cognitive function may be, at least in part, due to vascular defects, impaired insulin metabolism and signaling pathway or a defect in glucose transport mechanisms in brain. This review examines the available data regarding the impact of obesity on cognitive function.