MAPT and Alzheimer disease: As such, our observations surrounding NfL are confined to a late portion of the AD continuum, one potentially also confounded by brain pathologies other than amyloid-β and tau (e.g., α-synuclein, TDP-43 and vascular lesions) (James et al. 2016), which have been shown to increase in prevalence with age (Schneider et al. 2007) and involve brain regions not examined in this study.