Alzheimer's Biomarkers and Visuospatial Cognition in Parkinson's Disease: Modification by α‐Synuclein and Mediation of Age Effects

AD and α-synuclein biomarkers show associations consistent with synergistic effects on visuospatial cognition in PD. These findings are exploratory and require replication in pre-specified independent cohorts. However, if validated, testing both biomarkers could help identify individuals at higher risk of early visuospatial decline and inform hypothesis-driven stratification in future clinical trials.