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 When a sporadic event changes the course of Alzheimer's disease

A defining trait of Alzheimer's disease is the cerebral accumulation of amyloid-β proteins, which fragilize neurons and ultimately cause memory loss.

In a new study performed in a mouse model and published in Acta Neuropathologica Communications, researchers from the Neurodegenerative Diseases Laboratory (MIRCen) have shown that the experimental transmission of abnormal amyloid-β proteins accelerates, over time, the development of cerebral lesions and memory disorders. Their results suggest that sporadic events can change the course of Alzheimer's disease.

Published on 3 July 2023

Alzheimer's disease affects close to 36 million people worldwide. The disease is heterogenous, showing a range of origins, clinical courses and lesion profiles. Today still, the factors affecting its clinical course remain poorly understood.

A hallmark of Alzheimer's disease is the presence of amyloid-β (Aβ) protein deposits in the brain. These deposits set off a cascade of events that leads to synapse loss (thus limiting inter-neuron communication) and ultimately to failing memory and impeded daily function. Several studies have established that the intracerebral administration of Aβ-contaminated compounds can induce Aβ pathologies.

Some people have genetic mutations that can induce the production of mutated forms of Aβ. In their recent work performed in a murine amyloid pathology model, the LMN's MIINDt team (MIRCen) showed that a single exposure to certain forms of mutated Aβ can aggravate Alzheimer's disease lesions and other downstream aspects, notably as concerns cognition, functional connectivity and synaptic density, several months after the inoculation event. Moreover, the mutated Aβ appears to increase native Aβ aggregation. Obviously, the inoculation of mutated Aβ into the brain lacks clinical pertinence. However, the study does demonstrate how a single event regulating Aβ aggregation and synaptic health can have long-term impact, and furthermore has the originality of demonstrating behavioral effects.

This first study shows that a single sporadic event like mutated Aβ inoculation can aggravate the evolution of Alzheimer's disease and affect the clinical course months after the event itself. Its importance resides in its suggestion that Aβ is able to initiate mechanisms regulating a cascade of events over a long period. Further studies are now needed to determine the relationships between mutated Aβ and its functional effects.


Contact CEA : Marc Dhenain

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