LOSS OF VESSEL WALL VIABILITY IN CEREBRAL AMYLOID ANGIOPATHY

CEREBRAL amyloid angiopathy (CAA) is a neuropathological feature of Al zeheimer's disease and an important cause of cerebral haemorrhage in t he elderly. CAA is characterized by the deposition of Alzheimer amyloi d beta protein (A beta) in cerebral and leptomeningeal vessel walls. I n order to study the effect of cerebrovascular A beta deposits in vivo , living canine leptomeninges obtained from old dogs affected by CAA w ere analysed by confocal laser scanning microscopy after immunofluores cence staining for A beta and viability staining with fluorescein diac etate (FDA). Simultaneous detection of the two signals showed a segmen tal loss of leptomeningeal vessel wall viability at some site of A bet a deposition. Many of the non-viable vessels segments were also dilate d, suggesting that A beta-induced vascular cell death creates the loci minores resistentiae for the development of cerebral haemorrhage in C AA.