In each study, eligible participants were invited to undergo MRI scans, which were performed and interpreted in a standardized fashion without knowledge of demographic or clinical information (Appendix, Section 2). Infarct on MRI scan was defined as an area of abnormal signal intensity in a vascular distribution that lacked mass effect. Infarcts had to be 3–4 millimeters in size or greater. Efforts were made in all studies to distinguish infarcts from dilated perivascular spaces. All participants were categorized as having or not at least 1 MRI-infarct.
