Fig. 1: Conceptual framework: hallmarks of aging.

Aging is associated with a complex network of interrelated processes classified into three categories: primary hallmarks (blue) such as genomic instability, telomere attrition, epigenetic alterations and loss of proteostasis are considered potential initiating triggers. Antagonistic hallmarks (green), including deregulated nutrient sensing, mitochondrial dysfunction and cellular senescence, are responses that can be beneficial in moderation but become harmful when exacerbated. Integrative hallmarks (red), such as stem cell exhaustion, altered intercellular communication, chronic inflammation and dysbiosis, are thought to contribute to tissue dysfunction and organismal decline. This framework provides a conceptual model to describe the multifactorial nature of aging, though causal relationships remain under investigation.