Midlife vascular risk factors and Alzheimer's disease: evidence from epidemiological studies.

The shared risk factor profile between cardiovascular diseases and Alzheimer's disease (AD), observations on vascular pathology in AD, and altered cerebral blood flow in AD brains have led to the suggestion that AD might be a vascular disorder with neurodegenerative consequences. Targeting vascular and metabolic risk factors could be an effective way to prevent AD. Higher body mass index, elevated blood pressure, serum cholesterol concentrations, and impaired glucose regulation have been associated with increased risk of AD. Interestingly, the associations between these factors measured at mid-life are stronger, or even opposite, than with the risk factors measured at late-life. This may reflect true differences in the association (i.e., mid-life risk factors being a better measure of vascular load during adulthood), reverse causality, or bias. The vascular risk factors can directly increase the susceptibility to AD, or the effect can be mediated via cardio- and cerebrovascular diseases.