Amyloid-related imaging abnormalities (ARIA) are MRI findings that emerged as a major safety issue in anti-amyloid monoclonal antibody trials for Alzheimer's disease.[1][2] ARIA is usually divided into ARIA-E, which reflects vasogenic edema or sulcal effusions, and ARIA-H, which includes microhemorrhages and superficial siderosis.[1:1][3]
ARIA-E appears as parenchymal edema or sulcal effusion on MRI and is the subtype most strongly associated with symptomatic presentations such as headache, confusion, visual symptoms, or focal neurologic complaints.[1:2][2:1] The edema is typically vasogenic in nature, reflecting increased vascular permeability rather than true inflammatory changes.
Imaging characteristics include:
ARIA-H refers to hemosiderin-related findings including microhemorrhages and superficial siderosis. It is often asymptomatic but clinically important because it reflects vascular fragility and may alter risk-benefit decisions for continued anti-amyloid treatment.[1:4][3:2]
Imaging features include:
The leading model is that vascular amyloid burden, vessel-wall injury, and therapy-driven amyloid mobilization interact to increase vascular permeability and hemorrhagic risk.[1:5][2:2][4:1] This is why ARIA is often discussed along a continuum with cerebral amyloid angiopathy.[4:2]
Proposed mechanisms include:
Most cases are detected on protocol MRI rather than by symptoms.[1:9][3:6] Standard monitoring includes:
Management typically follows a severity-based protocol:
Corticosteroids (e.g., dexamethasone, methylprednisolone) are sometimes used in symptomatic cases to reduce edema and inflammation.[4:6]
Patients presenting with symptoms may require:
ARIA represents one of the central constraints on anti-amyloid treatment deployment:
ARIA matters across pages about lecanemab, donanemab, aducanumab, and broader amyloid immunotherapy vaccines for Alzheimer's disease, because it is one of the central constraints on anti-amyloid treatment deployment.
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Sperling RA, Jack CR Jr, Black SE, et al. Amyloid-related imaging abnormalities in patients with Alzheimer's disease treated with bapineuzumab: a retrospective analysis. Lancet Neurology. 2012;11(3):241-249. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Barakos J, Purcell D, Suhy J, et al. Amyloid-related imaging abnormalities (ARIA): radiological, biological and clinical characteristics. Brain Communications. 2023;5(4):fcad188. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Montagna M, Saveriano A, Mazzoleni S, et al. Spontaneous and Drug-Induced Amyloid-Related Imaging Abnormalities: Overlaps, Divergences, and Clinical Implications Across a Continuum Between Alzheimer's Disease and Cerebral Amyloid Angiopathy. Life (Basel). 2025;15(4):560. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
van Dyck CH, Swanson CJ, Aisen P, et al. Lecanemab in Early Alzheimer's Disease. New England Journal of Medicine. 2023;388:9-21. ↩︎
Sims JR, Zimmer JA, Evans CD, et al. Donanemab in Early Symptomatic Alzheimer's Disease. New England Journal of Medicine. 2023;389:124-135. ↩︎