STUB1 and early-onset autosomal dominant Alzheimer disease: Ultimately, our review clarifies that CHIP is not a simple protective factor, but a complex systemic modulator that reshapes the neurodegenerative and vascular drivers of cognitive decline, necessitating cross-disciplinary neuro-hematology collaboration to establish its role as a novel risk stratificator for improving diagnostic precision and personalizing clinical outcomes in Alzheimer's disease.