Amyloid Related Imaging Abnormalities (Aria) is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Amyloid-Related Imaging Abnormalities (ARIA) are MRI findings observed in patients receiving anti-amyloid immunotherapy for Alzheimer's disease. ARIA encompasses two subtypes — ARIA-E (edema/effusion) and ARIA-H (hemorrhage/hemosiderosis) — and represents the most significant safety concern associated with monoclonal antibodies targeting amyloid-beta (Aβ), including lecanemab (Leqembi), donanemab (Kisunla), and aducanumab (Aduhelm) (Sperling et al., 2011; Sperling et al., 2019). [1] [2]
Understanding ARIA is critical as anti-amyloid therapeutics enter routine clinical practice. While most cases are asymptomatic and resolve with appropriate management, severe ARIA can cause serious neurological complications and, rarely, death. The emergence of ARIA as a clinical entity has reshaped how anti-amyloid therapies are administered and monitored. [2:1] [3]
ARIA-E refers to amyloid-related imaging abnormalities with edema or sulcal effusion, appearing as hyperintense signal on T2-weighted FLAIR MRI sequences (Barakos et al., 2022): [3:1] [4]
ARIA-H encompasses hemorrhagic or hemosiderotic changes detected on susceptibility-weighted imaging (SWI) or T2*-weighted gradient echo MRI: [5] [5:1]
The two subtypes frequently co-occur — approximately 40-50% of patients with ARIA-E also develop ARIA-H. ARIA-H may persist after ARIA-E resolves, as hemosiderin deposits are permanent. [7] [6:1]
The leading hypothesis links ARIA to the interaction between anti-amyloid antibodies and cerebral amyloid angiopathy (CAA) (Greenberg et al., 2017; Barakos et al., 2022): [8] [7:1]
Additional immunological processes contribute to ARIA: [8:1]
Lecanemab (biweekly infusions): [9:1]
Donanemab (monthly infusions): [10]
Asymptomatic ARIA-E: [11]
Symptomatic ARIA-E: [12]
ARIA-H (microbleeds):
Permanent discontinuation indications:
Lecanemab is a humanized monoclonal antibody targeting soluble Aβ protofibrils, approved by the FDA in January 2023 (accelerated) and July 2023 (traditional approval), and by the EMA in late 2024:
The study of Amyloid Related Imaging Abnormalities (Aria) has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
van Dyck CH et al. Lecanemab in Early Alzheimer's Disease (2023). 2023. ↩︎
Hampel H et al. Amyloid-related imaging abnormalities (ARIA): radiological, biological and clinical characteristics (2023). 2023. ↩︎ ↩︎
Sims JR et al. Donanemab in Early Symptomatic Alzheimer's Disease (2023). 2023. ↩︎ ↩︎
Cummings J et al. Lecanemab: Appropriate Use Recommendations (2023). 2023. ↩︎ ↩︎
Wang H et al. The effect of modified donanemab titration on ARIA (2025). 2025. ↩︎ ↩︎
Cogswell PM et al. Amyloid-Related Imaging Abnormalities with Emerging AD Therapeutics (2022). 2022. ↩︎ ↩︎
Cogswell PM et al. Alzheimer's Disease Anti-Amyloid Immunotherapies: Imaging Recommendations (2025). 2025. ↩︎ ↩︎
Zimmer JA et al. Amyloid-Related Imaging Abnormalities With Donanemab (2025). 2025. ↩︎ ↩︎