REN and Alzheimer disease: Empirical studies have indicated that the dysregulated activation of the renin-angiotensin system within the central nervous system, coupled with neuroinflammatory responses—characterized by the proliferation of microglia and astrocytes—and the impairment of the blood–brain barrier, constitute the fundamental mechanisms driving the pathological advancement of AD (Ma et al., 2023; Zheng and Wang, 2025).