1 min readAlzheimer’s Disease: An Alternative Hypothesis Based on Synaptic Alterations

Genève, Switzerland — New research published today in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association could explain why neurons fail to communicate effectively in people with Alzheimer’s disease (AD). The study conducted by researchers in the laboratory of Christophe Mulle at the Interdisciplinary Institute of Neuroscience in Bordeaux opens a new research path to establish the molecular mechanism causing AD.
 
Despite intense efforts in clinical research, there is no treatment to cure or even slow down the progression of AD. Current clinical interventions are typically based on the ‘amyloid cascade’ hypothesis, postulating that neurodegeneration in AD is caused by the abnormal accumulation of amyloid plaques in the brain. However, these interventions have failed to demonstrate clinical efficacy. Recently, the European Medicines Agency did not approve a controversial new drug for AD that targets plaques, concluding that the benefits do not outweigh the risks. The decision leaves an estimated 8 million people living with dementia in the EU with no treatment options, highlighting the urgent need for an alternative target for AD research.
 
The new study reveals that the amyloid peptide composing the plaques is not the only offender accumulating in the human AD brain. Its precursor, the amyloid precursor protein (APP), was found to surround amyloid plaques in intense microscopic staining.
 
“Remarkably, our research revealed that the areas of the brain where APP accumulates, contain abnormal amounts of proteins essential for the communication between neurons,” said Dr. Gael Barthet senior author on the paper, now Director of Neuroscience at the Wyss Center.
 
The communication between neurons occurs at junctions called synapses where neurotransmitters released by a pre-synaptic neuron cross the junction to activate a post-synaptic neuron.
 
“What we found fascinating was that APP accumulated with excess of presynaptic proteins whereas post-synaptic proteins where depleted, indicating severe impairment of neuronal communication at these sites,” said Dr. Tomas Jorda, lead author of the paper and Post-Doctoral Research Associate in neurobiology at the University of Geneva.
 
“The new findings introduce a new direction for us to explore using our innovative, multi-scale, multi-modal approach at the Center,” said Dr. Richie Kohman, Chief Scientific Officer at the Wyss Center.

Article adapted from a Wyss Center for Bio and Neuroengineering news release.

Publication: APP accumulates with presynaptic proteins around amyloid plaques: A role for presynaptic mechanisms in Alzheimer’s disease? Tomàs Jordà-Siquier et al. Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association(January 2022): Click here to view.

Alzheimer's disease (AD), Amyloid plaques, Amyloid Precursor Protein (APP)

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