From the Guidelines
Cerebral amyloid angiopathy (CAA) is a condition characterized by the deposition of β-amyloid peptide in the walls of arterioles and capillaries in the leptomeninges, cerebral cortex, and cerebellar hemispheres, primarily affecting older adults and increasing the risk of brain hemorrhages, strokes, and cognitive impairment. This condition is one of the two common cerebral small vessel pathologies, along with arteriolosclerosis, that account for the majority of primary intracerebral hemorrhage (ICH) 1. The primary risk factors for CAA are age and apolipoprotein E genotypes containing the ε2 or ε4 alleles 1.
Key Characteristics of CAA
- Defined by deposition of β-amyloid peptide in the walls of arterioles and capillaries
- Primarily affects the leptomeninges, cerebral cortex, and cerebellar hemispheres (lobar territories)
- Increases the risk of brain hemorrhages, strokes, and cognitive impairment
- Related to the same amyloid protein found in Alzheimer's disease, though they are distinct disorders
Clinical Implications
- CAA is often discovered incidentally during brain imaging or after a person experiences symptoms like sudden headaches, weakness, confusion, or seizures
- Management focuses on preventing complications through blood pressure control, avoiding blood thinners when possible, and treating symptoms as they arise
- There is currently no specific treatment to remove the amyloid deposits, and the condition progresses gradually over years with varying severity among affected individuals 1.
From the Research
Definition and Classification of Cerebral Amyloid Angiopathy (CAA)
- Cerebral amyloid angiopathy (CAA) is a disorder characterized by the accumulation of amyloid proteins in the small and medium-sized blood vessels of the leptomeninges and central nervous system 2.
- CAA is classified into several types according to the cerebrovascular amyloid proteins involved, including sporadic amyloid β-protein (Aβ)-type CAA and familial forms such as Dutch-type hereditary cerebral hemorrhage with amyloidosis (HCHWA-D) and Icelandic-type HCHWA (HCHWA-I) 3, 2.
- Amyloid proteins associated with CAA include amyloid β protein (Aβ), immunoglobulin light chains, cystatin C, prion protein (PrP), ABri/ADan, transthyretin, and gelsolin 2, 4.
Pathological Features and Clinical Manifestations of CAA
- Deposited amyloid proteins damage smooth muscle cells in blood vessel walls, leading to pathological appearances such as 'double-barreled' changes, fibrinoid necrosis, and microaneurysms 2.
- CAA-related disorders include hemorrhagic and ischemic stroke, dementia, and recurrent hemorrhage 3, 2.
- Clinical manifestations of CAA include lobar intracerebral hemorrhage, brain ischemia, cognitive decline, and CAA-related inflammation 3, 5, 6.
Diagnosis and Imaging of CAA
- Sensitive magnetic resonance imaging procedures, such as gradient-echo T2* imaging and susceptibility-weighted images, are useful to detect microhemorrhagic lesions 3.
- Amyloid images with amyloid-binding positron emission tomography ligands can detect CAA, although they cannot discriminate vascular from parenchymal amyloid deposits 3.
- The Boston criteria have established diagnostic value and have been updated to version 2.0, and imaging markers depicted on CT and MRI techniques are crucial to evaluate the probability and severity of CAA 6.