While the trending decrease in CSF levels of NfL, a marker of axonal damage that is elevated in CSF47 and plasma48 of individuals with mild cognitive impairment, Alzheimer’s dementia, and other neurodegenerative disorders49, further suggests a benefit due to 3TC treatment, we note that the trending change in NfL due to 3TC treatment is discordant between CSF and plasma. This evidence concerns the gene NEFL and Alzheimer disease.