Alzheimer’s Disease: The Pathogenic Mechanism of β-amyloid Protein Deposition and Plaque Formation

Abstract

Alzheimer’s disease (AD) is a common chronic neurodegenerative disorder with a complex pathogenesis. The progression of AD is closely related to the dysregulation of gene expressions such as β-amyloid precursor protein, presenilin 1, and presenilin 2. The core pathogenic mechanisms mainly involve two key pathways: abnormal deposition of β-amyloid protein (Aβ) in the brain, forming senile plaques, and excessive phosphorylation of Tau protein, inducing neurofibrillary tangles. Together, these two factors lead to neuronal damage and necrosis, as well as atrophy of brain tissue structure, ultimately resulting in cognitive decline in patients. This article focuses on the core dimension of β-amyloid deposition and plaque formation in the core pathogenic mechanism of AD and systematically elaborates on it, while also considering the pathogenic role of abnormal Tau protein. Firstly, Aβ is a peptide fragment composed of 39 to 43 amino acid residues produced by the hydrolysis of amyloid precursor protein by β-secretase, which is the main component of senile plaques in AD. Aβ42 is prone to form neuronal plaques, while Aβ40 tends to deposit in the cerebral vessels. Abnormal accumulation can cause significant neurotoxicity. Secondly, the pathogenic mechanism is analyzed. Due to the imbalance between Aβ production and its clearance, it accumulates abnormally in brain regions related to memory and cognition, such as the cerebral cortex and hippocampus, forming plaques. This disrupts neuronal signal transmission, damages synaptic functions, and triggers inflammatory responses, accelerating nerve damage. Moreover, insufficient sleep reduces the efficiency of Aβ clearance and increases the risk of deposition. Additionally, treatment directions such as inhibiting ubiquitin-binding enzyme UBE2N and applying Aβ-targeted clearance drugs, as well as the application value of serum Aβ as an early peripheral biomarker, are discussed. The principles, classifications, and application scenarios of two core detection techniques, namely enzyme-linked immunosorbent assay and APOE genotyping, are elaborated. At the same time, the pathogenic mechanism of Tau protein over-phosphorylation, losing normal function, aggregating to form neurofibrillary tangles, and subsequently destroying the neuronal transport system, leading to cell death, is also explained. This provides theoretical support and practical references for the early risk assessment of AD, deepening exploration of its pathological mechanism, and the development of targeted treatment plans.