Fig. 1.

Study design and participant selection. Participants completed 3T MRI beginning in 2008, and the standardized cognitive battery beginning in 2005. The majority of plasma biomarker measurements occurred in 2009; however, some participant samples were as early as 2005. For MRI analyses, the first plasma biomarker visit for participants on or after age 50 at the time of collection, that also had a concurrent 3T MRI scan was selected as the baseline visit for brain volume analyses. Similarly, for cognition analyses, the first plasma biomarker visit for participants on or after age 50 at the time of collection, that also had a concurrent cognitive assessment was selected as the baseline visit for cognition analyses. Fig.created with BioRender.com