Cerebrovascular alterations in Alzheimer disease incidental or pathogenic?

Alzheimer disease (AD)-the leading cause of cognitive impairment in the elderly-has traditionally been considered a disease of neurons. Structural and functional alterations of cerebral blood vessels also occur, but direct evidence of a causal involvement in the pathobiology of the disease has been lacking. This viewpoint will review new data that may help shed light into the intriguing association between vascular and neurodegenerative pathology.