Compared with normal cognition, participants with MCI or AD were older, less educated, more likely to be women, less likely to smoke and drink alcohol, had lower estimated glomerular filtration rate and plasma Aβ42/Aβ40 ratio, and higher plasma Aβ40 and NfL concentrations (p < 0.05) (Table 1). This evidence concerns the gene NEFL and Alzheimer disease.