This study aimed to determine age-specific normative values for serum neurofilament light chain (sNfL) levels in a representative sample of US adults and to evaluate the associations between sNfL and sociodemographic characteristics. Using data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2013 and 2014, the researchers analyzed serum samples from 2071 adult participants. General linear models were used to examine the relationships between sNfL levels and various demographic factors. The results showed a significant positive association between age and sNfL levels (p<0.001), with mean sNfL levels increasing nonlinearly with age. Sex was also associated with sNfL levels (p=0.04), with males having higher mean sNfL levels (17.99 pg/mL) compared to females (15.78 pg/mL) after controlling for age. No significant relationships were found between sNfL levels and other factors such as race/ethnicity, family income, education level, BMI, or nicotine use. The study provides a baseline for comparing sNfL levels in clinical practice and future research, highlighting the importance of considering potential confounders that may impact the biomarker's interpretation.This study aimed to determine age-specific normative values for serum neurofilament light chain (sNfL) levels in a representative sample of US adults and to evaluate the associations between sNfL and sociodemographic characteristics. Using data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2013 and 2014, the researchers analyzed serum samples from 2071 adult participants. General linear models were used to examine the relationships between sNfL levels and various demographic factors. The results showed a significant positive association between age and sNfL levels (p<0.001), with mean sNfL levels increasing nonlinearly with age. Sex was also associated with sNfL levels (p=0.04), with males having higher mean sNfL levels (17.99 pg/mL) compared to females (15.78 pg/mL) after controlling for age. No significant relationships were found between sNfL levels and other factors such as race/ethnicity, family income, education level, BMI, or nicotine use. The study provides a baseline for comparing sNfL levels in clinical practice and future research, highlighting the importance of considering potential confounders that may impact the biomarker's interpretation.