SNCA and Alzheimer disease: Longitudinal data across the life course to assess the incidence, severity, and trajectories of loneliness along with the incidence, severity, and location of cerebrovascular disease, may provide insight into the additive and/or synergistic effects with AD pathology and other concurrent pathologies (e.g., other vascular pathologies beyond infarcts and microinfarcts, TAR DNA‐binding protein 43 (TDP‐43), alpha‐synuclein).