MAPT and Alzheimer disease: Molecular hallmarks of brain aging encompass telomere shortening, oxidative stress resulting from reactive oxygen species (ROS) accumulation, neuroinflammation propelled by chronic microglial activation, dysregulated mitochondrial homeostasis, impaired autophagy, and the pathological accumulation of misfolded proteins like amyloid-beta (Aβ) and tau, which are central to Alzheimer’s disease (AD) and other neurodegenerative conditions.