NfL is a nonspecific AD biomarker often associated with vascular aspects of dementia and indicative of the neurodegenerative processes of axonal injuries.9,45,46,47,48 Our findings demonstrated that APOE4 carriers with higher NfL levels had a significantly greater rate of cognitive decline than noncarriers with the same NfL levels. The gene discussed is NEFL; the disease is Alzheimer disease.