Serologic biomarkers that have been reported to reflect neuropathological processes include CCL23 in acute ischemic stroke, phosphorylated tau and amyloid-β in AD, and NfL levels in relapsing–remitting MS (Ashton et al., 2021; Kuhle et al., 2019; Simats et al., 2018). Here, MAPT is linked to Alzheimer disease.