MAPT and early-onset autosomal dominant Alzheimer disease: Limited biomarker selection: The study focused solely on exercise-related biomarkers, namely serum brain-derived neurotrophic factor (BDNF) and platelet factor 4 (PF4), excluding the inclusion of characteristic biomarkers of Alzheimer’s disease (AD) such as β-amyloid (Aβ) and phosphorylated tau (p-tau).