Brain Hemorrhages in Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is cerebrovascular amyloid deposition. It is classified into several types according to the cerebrovascular amyloid proteins involved. Sporadic amyloid β-protein (Aβ)-type CAA is commonly found in elderly individuals and patients with Alzheimer disease. CAA-related disorders include hemorrhagic and ischemic stroke and dementia. CAA-related hemorrhages include intracerebral lobar macrohemorrhages, cortical microhemorrhages, and focal subarachnoidal hemorrhages/superficial siderosis. CAA-associated vasculopathies, such as microaneurysmal formation with fibrinoid necrosis, underlie such cerebrovascular events. Sensitive magnetic resonance imaging procedures, such as gradient-echo T2* imaging and susceptibility-weighted images, are useful to detect microhemorrhagic lesions. Amyloid images with amyloid-binding positron emission tomography ligands can detect CAA, although they cannot discriminate vascular from parenchymal amyloid deposits. Hemorrhage-inducing factors for sporadic Aβ-type CAA include apolipoprotein E genotype, thrombolytic, anticoagulation, and antiplatelet therapies, hypertension, minor head trauma, and antiamyloid therapies. We need future strategies for protection of vessel walls against amyloid-related vascular damage, such as toxicity of Aβ oligomers, Aβ-induced oxidative stress, and inflammation, as well as development of antiamyloid therapies for CAA.