Amyloid-Related Imaging Abnormalities (ARIA)

Amyloid-Related Imaging Abnormalities (ARIA)

<div class="infobox infobox-disease">
<div class="infobox-header">Amyloid-Related Imaging Abnormalities (ARIA)</div>
<div class="infobox-row">
<div class="infobox-label">Context</div>
<div class="infobox-value">MRI abnormalities associated with anti-amyloid therapy and cerebral amyloid angiopathy-related vascular fragility</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Main subtypes</div>
<div class="infobox-value">ARIA-E (edema/effusion) and ARIA-H (microhemorrhage/siderosis)</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Major risk factors</div>
<div class="infobox-value">APOE ε4 carriage, higher antibody dose, baseline microhemorrhages, vascular amyloid burden</div>
</div>
</div>

Overview

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](/diseases/alzheimers-disease).[@antibodybased][@amyloidrelated] ARIA is usually divided into ARIA-E, which reflects vasogenic edema or sulcal effusions, and ARIA-H, which includes microhemorrhages and superficial siderosis.[@antibodybased][@regulatory]

Types

ARIA-E

Amyloid-Related Imaging Abnormalities (ARIA)

<div class="infobox infobox-disease">
<div class="infobox-header">Amyloid-Related Imaging Abnormalities (ARIA)</div>
<div class="infobox-row">
<div class="infobox-label">Context</div>
<div class="infobox-value">MRI abnormalities associated with anti-amyloid therapy and cerebral amyloid angiopathy-related vascular fragility</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Main subtypes</div>
<div class="infobox-value">ARIA-E (edema/effusion) and ARIA-H (microhemorrhage/siderosis)</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Major risk factors</div>
<div class="infobox-value">APOE ε4 carriage, higher antibody dose, baseline microhemorrhages, vascular amyloid burden</div>
</div>
</div>

Overview

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](/diseases/alzheimers-disease).[@antibodybased][@amyloidrelated] ARIA is usually divided into ARIA-E, which reflects vasogenic edema or sulcal effusions, and ARIA-H, which includes microhemorrhages and superficial siderosis.[@antibodybased][@regulatory]

Types

ARIA-E

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.[@antibodybased][@amyloidrelated] The edema is typically vasogenic in nature, reflecting increased vascular permeability rather than true inflammatory changes.

Imaging characteristics include:

• Hyperintense signal on FLAIR sequences
• Typically cortical or subcortical in location
• Often in posterior brain regions
• May be accompanied by sulcal effusions[@antibodybased][@regulatory]

ARIA-H

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.[@antibodybased][@regulatory]

Imaging features include:

• Small hypointense foci on T2* GRE or SWI sequences
• Superficial siderosis presenting as hemosiderin deposition along leptomeningeal surfaces
• Often distributed in lobar regions (cortical)[@regulatory][@trem]

Why ARIA Happens

The leading model is that vascular amyloid burden, vessel-wall injury, and therapy-driven amyloid mobilization interact to increase vascular permeability and hemorrhagic risk.[@antibodybased][@amyloidrelated][@trem] This is why ARIA is often discussed along a continuum with [cerebral amyloid angiopathy](/diseases/cerebral-amyloid-angiopathy).[@trem]

Proposed mechanisms include:

Risk Factors

• [APOE](/proteins/apoe) ε4 carriage, especially homozygosity (2-3x elevated risk)[@antibodybased][@amyloidrelated]
• Higher anti-amyloid dose exposure[@amyloidrelated][@regulatory]
• Baseline microhemorrhages or other vascular amyloid markers[@antibodybased]
• Early treatment phase, when most ARIA events are first detected (first 3-6 months)[@antibodybased][@regulatory]
• Female sex (observed in some studies)
• Prior cerebral hemorrhage history[@trem]

Clinical Management

Detection and Monitoring

Most cases are detected on protocol MRI rather than by symptoms.[@antibodybased][@regulatory] Standard monitoring includes:

• Baseline MRI before initiating treatment
• Periodic MRI scans (typically at weeks 4, 8, 12, then quarterly)
• Symptom-driven imaging if neurological changes occur[@antibodybased]

Treatment Approach

Management typically follows a severity-based protocol:

• Mild/moderate ARIA-E: Dose interruption, close monitoring, repeat MRI
• Severe ARIA-E: Discontinue treatment, consider corticosteroids
• ARIA-H: Risk-benefit assessment, may require treatment discontinuation[@antibodybased][@trem]

Symptomatic Management

Patients presenting with symptoms may require:

• Neurological evaluation
• Supportive care
• Management of complications (seizures, edema)
• Multidisciplinary input (neurology, radiology, geriatrics)[@antibodybased]

Implications for Anti-Amyloid Therapies

ARIA represents one of the central constraints on anti-amyloid treatment deployment:

Lecanemab (Leqembi)

• ARIA-E incidence: ~10% (placebo ~1%)
• ARIA-H incidence: ~17% (placebo ~8%)
• Higher risk in APOE ε4 carriers[@relationship]

Donanemab (Kisunla)

• Similar ARIA profile to [lecanemab](/entities/lecanemab)
• ARIA more common in first 6 months
• Risk mitigation through APOE testing and MRI monitoring[^6]

Aducanumab (Aduhelm)

• Higher doses associated with more ARIA
• Led to label restrictions and withdrawal from market[@amyloidrelated]

Relevance to the Wiki

ARIA matters across pages about [lecanemab](/therapeutics/lecanemab), [donanemab](/therapeutics/donanemab), [aducanumab](/therapeutics/aducanumab), and broader [amyloid immunotherapy vaccines for Alzheimer's disease](/therapeutics/amyloid-vaccines), because it is one of the central constraints on anti-amyloid treatment deployment.

See Also

• [Amyloid Immunotherapy Vaccines for Alzheimer's Disease](/therapeutics/amyloid-vaccines)
• [Aducanumab (Aduhelm)](/therapeutics/aducanumab)
• [Lecanemab (Leqembi)](/therapeutics/lecanemab)
• [Donanemab (Kisunla)](/therapeutics/donanemab)
• [Cerebral Amyloid Angiopathy (CAA)](/diseases/cerebral-amyloid-angiopathy)
• [Alzheimer's Disease](/diseases/alzheimers-disease)

External Links

• [Wikipedia](https://en.wikipedia.org/)
• [NCBI Resources](https://www.ncbi.nlm.nih.gov/)

Recent Research (2024-2026)

This section highlights recent publications relevant to this disease.

• [Antibody-based nanoparticles in Alzheimer's disease: Innovations in diagnosis and therapy.](https://pubmed.ncbi.nlm.nih.gov/41762606/) (2026 May) - Pathology, research and practice
• [Amyloid-related imaging abnormalities (ARIA) in Alzheimer's immunotherapy: a framework and challenges for global surveillance strategies.](https://pubmed.ncbi.nlm.nih.gov/41571449/) (2026 Mar 13) - Journal of neurology, neurosurgery, and psychiatry
• [Regulatory, clinical, and post-marketing challenges of lecanemab for Alzheimer's disease: insights from real-world data.](https://pubmed.ncbi.nlm.nih.gov/41787137/) (2026 Mar 6) - Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology
• [The TREM2 agonistic antibody AL002 in early Alzheimer's disease: a phase 2 randomized trial.](https://pubmed.ncbi.nlm.nih.gov/41787076/) (2026 Mar 5) - Nature medicine
• [Relationship between APOE Genotype Status and Imaging Features in Patients with Alzheimer Disease Being Considered for Antiamyloid β Therapy.](https://pubmed.ncbi.nlm.nih.gov/41781178/) (2026 Mar 4) - AJNR. American journal of neuroradiology

References