Alzheimer’s disease (AD) is the leading cause of dementia and a heterogeneous neurodegenerative disorder characterized by amyloid-β (Aβ) and tau pathology, impaired proteostasis, neurovascular dysfunction, maladaptive glial and immune responses, and synaptic dysfunction. Human genetic evidence supports an upstream role for Aβ. Anti-Aβ monoclonal antibodies substantially reduce amyloid burden and modestly slow clinical decline in early symptomatic AD. Continued decline despite plaque removal is consistent with ongoing downstream tau pathology, glial responses, and neuronal injury. This narrative review examines AD mechanisms, biomarkers, and therapeutic prospects from a geroscience perspective and applies the eight hallmarks of neurodegenerative diseases as an analytical framework. Advances in blood-based biomarkers, particularly plasma phosphorylated tau 217, may improve biological detection, but their clinical value depends on assay performance, intended use, and patient context. Gut dysbiosis and gut–brain communication are considered separately as candidate systemic modifiers because causal evidence in humans remains insufficient. The hallmarks are overlapping analytical categories, not independent primary causes, and their therapeutic relevance depends on disease stage and pathway activity. Future studies should establish which preventive strategies and biomarker-guided, stage-matched combination therapies improve clinically meaningful outcomes and identify the patients most likely to benefit.
Cellular senescence is a context-dependent cellular state characterised by persistent cell-cycle arrest, epigenetic remodelling, metabolic reprogramming and acquisition of a senescence-associated secretory phenotype. Transient senescence contributes to embryogenesis, tissue repair and tumour suppression, whereas persistent senescent cell populations accumulate with advancing age across multiple tissues, in part owing to declining immune-mediated clearance and intrinsic resistance to apoptosis, thereby promoting chronic systemic inflammation, tissue fibrosis, stem-cell dysfunction and propagation of secondary senescence. Experimental genetic and pharmacological evidence supports a contributory and in several contexts causal role for senescent cells in cardiovascular, metabolic, musculoskeletal, fibrotic and neurodegenerative disorders. These findings have accelerated the development of senotherapeutic strategies, including senolytics, senomorphics and immune-mediated clearance approaches, with early clinical studies showing preliminary evidence of functional benefit in idiopathic pulmonary fibrosis and diabetic kidney disease. However, clinical translation remains constrained by senescence heterogeneity, limited biomarker specificity and unresolved long-term safety concerns. Improved molecular, spatial and functional resolution of senescent states will be essential for developing biomarker-guided and tissue-specific interventions that preserve the beneficial functions of transient senescence while limiting its chronic deleterious effects.
P. Chmielewski· Biogerontology (Dordrecht)· 1 citation
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