Plasma neurofilament light chain (NFL) is differentially associated with neuropsychological test performance among non‐Hispanic whites and hispanic, Mexican Americans: A HABLE study

Abstract

AbstractBackgroundNeurofilament light chain (NfL) has been examined as a biomarker of Alzheimer’s disease (AD) due to its link with neurodegeneration. Among a community sample of Mexican Americans, NfL was found to be inversely related to processing speed, attention, executive functioning, and memory among those with normal cognition (NC) as well as those with mild cognitive impairment (MCI). This study aimed to validate prior work and examine if the relationship between NfL and cognition differed by ethnicity when split by diagnostic status.MethodData were analyzed on n= 503 non‐Hispanic white (n=363 NC; n= 140 impaired cognition [MCI +dementia]) and n=357 Mexican American (n=187 NC; n=169 impaired cognition [MCI +dementia]) participants enrolled in a study of health disparities. Plasma NfL were assayed using Simoa. Neuropsychological test battery included Trail Making Test Part A and B, FAS, Animal Naming, Spanish and English Verbal Learning Test (Immediate and Delayed Recall), and Digit Symbol Substitution. Linear regression models analyzed cognitive test performance as the dependent variable while NfL was included as the independent variable. Covariates included age, gender, and education. Regression models were run separately for each cognitive test. Analyses were split by both ethnicity and diagnosis.ResultAmong non‐Hispanic whites with normal cognition, NfL was related to poorer neuropsychological test performance across measures of attention, processing speed, verbal fluency (FAS), and immediate memory. Among those with impaired cognition, NfL was associated with poorer performance across neuropsychological measures of attention, processing speed, executive functioning, and verbal fluency (animal naming). Among Hispanic, Mexican Americans with normal cognition, NfL was only found to be associated with poorer neuropsychological test performance on a measure of verbal fluency (animal naming). NfL was not found to be associated with any cognitive domain examined for Hispanic, Mexican Americans with impaired cognition.ConclusionThese findings highlight that biomarkers associated with AD, such as NfL, likely differ by ethnicity. This corresponds with our prior work that has shown lower rates of APOEe4 and amyloid among Hispanic, Mexican Americans. This further supports the need to examine more closely underlying biological mechanisms of neurodegenerative conditions among minority populations such as Hispanic, Mexican Americans.