MAPT and Alzheimer disease: 2025). In parallel, tau normally stabilizes microtubules but in AD becomes hyperphosphorylated, detaches, misfolds, and forms neurofibrillary tangles that impair axonal transport and promote neuronal death (W. Zhang et al. 2023). These molecular abnormalities are accompanied by cholinergic deficits, glial activation, and progressive atrophy in hippocampal and cortical networks that are essential for learning and memory (Sheppard and Coleman 2020).