Data collected every five years in the 30-year Betula study in Sweden reported that age-related changes in plasma NfL levels (measured by Simoa) are linked to brain white matter (WM) alterations using T1- and T2-weighted images.36 Alzheimer’s disease cases showed elevated levels compared with controls, but no significant differences from the preclinical phase. This evidence concerns the gene NEFL and early-onset autosomal dominant Alzheimer disease.