NEFL and Alzheimer disease: This exclusion may have made it difficult to detect subtle associations between plasma NFL and white matter pathologic findings and may explain the surprising finding that plasma NFL did not correlate with WMHs, despite that CSF NFL has been considered a marker of white matter pathologic features, including in AD. Future studies should test plasma NFL in a more unselected group of patients with AD and may also explore different proxies for white matter injury.