NEFL and Neurodevelopmental delay: 145 In a longitudinal study of 583 dementia-free older adults (330 with MCI), MBI was associated with a greater increase in plasma NfL levels.146 Although not in plasma, it should be noted that MBI participants exhibited CSF p-tau181, p-tau181/Aβ42 ratio, and tau/Aβ42 ratio trajectories consistent with NDD across two independent cohorts with MCI; in one cohort, MBI was also related to Aβ42 and Aβ42/40 changes over 4 years.