Several lines of evidence point to an underlying vascular component in the pathology of Alzheimer's disease (AD).Vascular diseases (hypertension, atherosclerosis, stroke) often precede or accompany the onset of AD. Endothelium dysfunction is an early event in these vascular diseases. An impaired endothelium response is also found in normal aging and Alzheimer's disease is an age dependent disease. We have shown that vascular dysfunction induced by the Alzheimer's peptide, b-amyloid (Ab), involves endothelial damage by superoxide radicals. Our current research is to investigate the mechanism of Ab induced dysfunction and the role of aging, stroke, and endogenous antioxidants (estrogen) in the Ab related vascular component of AD pathology