The origin and development of plaques and phosphorylated tau are associated with axonopathy in Alzheimer's disease

Objective The production of neurotoxic beta-amyloid and the formation of hyperphosphorylated tau are thought to be critical steps contributing to the neuropathological mechanisms in Alzheimer's disease (AD). However, there remains an argument as to their importance in the onset of AD. Recent studies have shown that axonopathy is considered as an early stage of AD. However, the exact relationship between axonopathy and the origin and development of classic neuropathological changes such as senile plaques (SPs) and neurofibrillary tangles (NFTs) is unclear. The present study aimed to investigate this relationship. Methods Postmortem tracing, combined with the immunohistochemical or immunofluorescence staining, was used to detect axonopathy and the formation of SPs and NFTs. Results Axonal leakage-a novel type of axonopathy, was usually accompanied with the extensive swollen axons and varicosities, and was associated with the origin and development of A beta plaques and hyperphosphorylated tau in the brains of AD patients. Conclusion Axonopathy, particularly axonal leakage, might be a key event in the initiation of the neuropathological processes in AD.