NEFL and Alzheimer disease: Increased serum and plasma levels of the NfL protein have been demonstrated in several neurodegenerative diseases including Alzheimer’s disease (AD) (Lewczuk et al., 2018; Forgrave et al., 2019; Moscoso et al., 2021), frontotemporal dementia (Forgrave et al., 2019), motor neuron disease (Forgrave et al., 2019) and traumatic brain injury (Shahim et al., 2018).