Preventing Alzheimer's disease by targeting vascular risk factors: hope and gap.

Alzheimer's disease (AD) is a major cause of functional dependence, poor quality of life, institutionalization, and mortality among elderly people. As a multifactorial disorder, AD has been frequently linked to vascular risk factors (e.g., smoking, hypertension, obesity, diabetes, hyperlipidemia, and inflammation) in numerous prospective cohort studies of the general population. Systematic reviews and meta-analyses of prospective studies have from the life-course perspective revealed an age-dependent association with the risk of AD for several vascular risk factors such as high blood pressure, obesity, and high total cholesterol, such that possessing these factors in mid-life, but not necessarily in late-life, is associated with an increased risk of AD. The biological plausibility for vascular risk factors to be involved in the pathogenesis and clinical manifestation of Alzheimer syndrome is partly supported by population-based neuroimaging and neuropathological studies. However, randomized controlled trials that target those major cardiovascular risk factors (e.g., antihypertensive, cholesterol-lowering, and anti-inflammatory therapies) have generally failed to prove as efficacious preventative approaches for AD. To bridge the gap, the multifactorial nature of AD and the proper time-window for intervention should be taken into account in the future when designing preventative interventions against this devastating disorder.