Detection of Alzheimer’s disease amyloid-beta plaque deposition by deep brain impedance profiling

OBJECTIVE: Alzheimer disease (AD) is the most common form of neurodegenerative disease in elderly people. Toxic brain amyloid-beta (ASS) aggregates and ensuing cell death are believed to play a central role in the pathogenesis of the disease. In this study, we investigated if we could monitor the presence of these aggregates by performing in situ electrical impedance spectroscopy measurements in AD model mice brains. APPROACH: In this study, electrical impedance spectroscopy measurements were performed post-mortem in APPPS1 transgenic mice brains. This transgenic model is commonly used to study amyloidogenesis, a pathological hallmark of AD. We used flexible probes with embedded micrometric electrodes array to demonstrate the feasibility of detecting senile plaques composed of ASS peptides by localized impedance measurements. MAIN RESULTS: We particularly focused on deep brain structures, such as the hippocampus. Ex vivo experiments using brains from young and old APPPS1 mice lead us to show that impedance measurements clearly correlate with the percentage of Abeta plaque load in the brain tissues. We could monitor the effects of aging in the AD APPPS1 mice model. SIGNIFICANCE: We demonstrated that a localized electrical impedance measurement constitutes a valuable technique to monitor the presence of Abeta-plaques, which is complementary with existing imaging techniques. This method does not require prior Abeta staining, precluding the risk of variations in tissue uptake of dyes or tracers, and consequently ensuring reproducible data collection.