Benedet, A. | Search bioRxiv

bioRxiv2025

Associations between fluid biomarkers and PET imaging (UCB-J) of synaptic pathology in Alzheimer's disease

INTRODUCTIONPositron Emission Tomography (PET) imaging with ligands for synaptic vesicle glycoprotein 2A (SV2A) has emerged as a promising methodology for measuring synaptic density in Alzheimers disease (AD). We investigate the relationship between SV2A PET and CSF synaptic protein changes of AD patients. METHODTwenty-one participants with early AD and 7 cognitively normal (CN) individuals underwent [11C]UCB-J PET. We used mass spectrometry to measure a panel of synaptic proteins in CSF. RESULTSIn the AD group, higher levels of syntaxin-7 and PEBP-1 were associated with lower global synaptic density. In the total sample, lower global synaptic density was associated with higher levels of AP2B1, neurogranin, {gamma}-synuclein, GDI-1, PEBP-1, syntaxin-1B, and syntaxin-7 but not with the levels of the neuronal pentraxins or 14-3-3 zeta/delta. CONCLUSIONReductions of synaptic density found in AD compared to CN participants using [11C]UCB-J PET were observed to be associated with CSF biomarker levels of synaptic proteins.

neuroscience↗

bioRxiv2023

Revealing the combined roles of Abeta and tau in Alzheimer's disease via a pathophysiological activity decoder

Neuronal dysfunction and cognitive deterioration in Alzheimers disease (AD) are likely caused by multiple pathophysiological factors. However, evidence in humans remains scarce, necessitating improved non-invasive techniques and integrative mechanistic models. Here, we introduce personalized brain activity models incorporating functional MRI, amyloid-{beta} (A{beta}) and tau-PET from AD-related participants (N=132). Within the model assumptions, electrophysiological activity is mediated by toxic protein deposition. Our integrative subject-specific approach uncovers key patho-mechanistic interactions, including synergistic A{beta} and tau effects on cognitive impairment and neuronal excitability increases with disease progression. The data-derived neuronal excitability values strongly predict clinically relevant AD plasma biomarker concentrations (p-tau217, p-tau231, p-tau181, GFAP). Furthermore, our results reproduce hallmark AD electrophysiological alterations (theta band activity enhancement and alpha reductions) which occur with A{beta}-positivity and after limbic tau involvement. Microglial activation influences on neuronal activity are less definitive, potentially due to neuroimaging limitations in mapping neuroprotective vs detrimental phenotypes. Mechanistic brain activity models can further clarify intricate neurodegenerative processes and accelerate preventive/treatment interventions.

neuroscience↗