Cellular elements of the neurovascular unit are essential for the physiological functioning of brain vessels. If any of these vascular elements are disturbed the consequences can be dire. Cerebral amyloid angiopathy (CAA), a disorder caused by the accumulation of amyloid in cerebral vessels, provides a case study of progressive neurovascular unit dysfunction leading to failure of vascular reactivity, smooth muscle cell loss, and eventual frank breakdown of vessel integrity resulting in recurrent and sometimes fatal intracerebral hemorrhage.