Amyloid-beta 42 (Aβ42) oligomers (Aβ42 oligomers)

Amyloid-beta 42 (Aβ42) oligomers are soluble, neurotoxic aggregates of the Aβ42 peptide, which is produced by the sequential cleavage of amyloid precursor protein (APP) by beta- and gamma-secretases (UniProt P05067). These oligomers are central to the amyloid cascade hypothesis of Alzheimer's disease, where they are thought to initiate a sequence of events including synaptic dysfunction, tau pathology, and neuroinflammation (PubMed: 29339413). Unlike insoluble plaques, soluble Aβ42 oligomers and protofibrils are highly mobile and can interact with various neuronal receptors, leading to impaired long-term potentiation and memory loss (PubMed: 30612635). In Alzheimer's disease, the accumulation of these species is a primary driver of neurodegeneration and cognitive decline (NIH/NIA). Therapeutic strategies have shifted toward targeting these specific aggregated forms rather than monomeric Aβ. Monoclonal antibodies such as lecanemab and donanemab have been developed to recognize and bind to aggregated Aβ42, facilitating their clearance from the brain by microglia (FDA, 2023/2024). Clinical trials have demonstrated that reducing the brain's burden of Aβ42 aggregates can modestly slow the rate of cognitive decline in early-stage patients (PubMed: 36630468). However, these therapies are associated with safety risks, most notably amyloid-related imaging abnormalities (ARIA), which require careful monitoring via MRI (PubMed: 33547031).

Other names

Aβ42 aggregatesAmyloid-beta 1-42 oligomersAβ42 protofibrilsSoluble Aβ42 oligomersAmyloid-beta 42 fibrilsAβ42 plaques

Monoclonal antibodies bind to specific epitopes on aggregated Aβ42 species (oligomers, protofibrils, or plaques) to facilitate microglia-mediated phagocytosis and clearance from the brain, thereby reducing neurotoxicity and slowing cognitive decline (FDA; PubMed: 36630468).