Blood-based biomarkers are increasingly used to characterize Alzheimer's disease (AD)-related pathology, yet substantial heterogeneity exists in how biomarker burden relates to cognitive performance. Grip strength, a marker of frailty and functional reserve, may modify this relationship. We conducted a cross-sectional analysis of 348 participants from the Aging Adult Brain Connectome (AABC) study. Global cognition was assessed using the Preclinical Alzheimer Cognitive Composite (PACC). Plasma bi...