Cerebral Amyloid Angiopathy (CAA)

Cerebral amyloid angiopathy is characterized by dementia in the setting of microhemorrhages and lobar hemorrhages.

• In cerebral amyloid angiopathy there is pathological invasion of amyloid beta in the walls of cerebral cortical small and medium-sized blood vessels and leptomeningeal arteries. We show amyloid in red because, as we discussed with Alzheimer's disease, it stains with Congo red staining (it is "congophilic").
• There is an important overlap between amyloid accumulation in Alzheimer's disease and in cerebral amyloid angiopathy.

Amyloid accumulation causes microaneurysm formation, rupture, and bleeding.

• Since bleeding is the primary pathology, we show an MRI sequence that highlights blood products (in black); show an axial gradient echo image (specifically, a susceptibility weighted image).
• We show a stippled appearance of micro-bleeds within the cerebral lobes, peripherally.
• Note that, as a helpful oversimplification, we can think of amyloid angiopathy as impacting the peripheral portion of the brain and multi-infarct dementia as impacting the central portion (mimicking a white matter disease). This distinction easily breaks down, however, when amyloid accumulates in small caliber vessels found centrally in perivascular spaces in the white matter.

We also show a large lobar hemorrhage, another important consequence of the amyloid angiopathy.