How molecular mechanisms of aging drive Alzheimer's disease pathology

Aging is a "multidimensional engine" of biological dysfunction that can fundamentally reshape the pathology of Alzheimer's disease (AD), This review systematically elaborates on how aging synergistically promotes the core pathologies of AD: aging upregulates the activity of β-secretase 1 (BACE1)/γ-secretase, impairs the clearance function of glial cells and meningeal lymphatic drainage, and accelerates Aβ deposition; the imbalance of kinases/phosphatases, dysfunction of molecular chaperones, and aging exosome-mediated propagation of Tau "seeds" facilitate Tau pathology; hyperreactivity of microglia and the transformation of astrocytes to the A1 phenotype form a senescence-associated secretory phenotype (SASP) → neuroinflammation vicious cycle; downregulation of synaptic proteins and disintegration of the default mode network lead to cognitive decline. Recent studies have identified that the impaired transition of aging microglia to the disease-associated microglia (DAM) phenotype, peripheral-central aging signal transmission loops (the gut-brain axis, immune-brain axis, and metabolic-brain axis), as well as circadian rhythm/vascular metabolic dysregulation, have emerged as novel intervention targets. Precision strategies targeting aging mechanisms-such as senescent cell clearance, SASP inhibition, epigenetic reprogramming, and biomarker-guided early intervention-provide a new paradigm for blocking the progression of AD.