Association between serum neurofilament light chain levels and grip strength among US adults: a cross-sectional study using National Health and Nutrition Examination Survey data from 2013 to 2014.

Objective: We aimed to investigate the relationship between serum neurofilament light chain (NfL) and grip strength using data from the 2013-2014 US National Health and Nutrition Examination Survey (NHANES).

Design: Secondary analysis of cross-sectional, population-based data.

Setting: NHANES sample, 2013-2014.

Participants: We studied 1925 participants aged 20-75 years.

Outcome measures and analysis: We applied a multivariable generalised linear regression model, adjusted for several potential confounders, and restrictive cubic spline models to evaluate the association between serum NfL and grip strength. Subgroup analyses were conducted using stratified multivariable linear regression analysis.

Results: We included 1925 participants (average age: 44.8±0.44 years) from the NHANES database. Participants with higher serum NfL levels had a significantly higher prevalence of medical conditions (hypertension, diabetes, cardiovascular disorder, chronic kidney disease (CKD) and cancer) compared with those with lower NfL levels (all p<0.001). After adjusting for confounding factors, there was a negative association between serum NfL and grip strength (β=-2.07; 95% CI -3.47, -0.67; p=0.007). In addition, significant interactions were found between NfL and grip strength stratified by age, physical activity and CKD (p value for interaction=0.002, 0.023 and 0.006). The results of the restricted cubic splines (RCS) analysis showed no evidence against a linear association of serum NfL levels with grip strength. (p for non-linearity=0.334).

Conclusion: Our study demonstrates a strong, negative and linear correlation between elevated serum NfL levels and grip strength. Notably, our findings indicate that individuals aged between 60 and 75 years, those with physical inactivity and those with CKD exhibit a more pronounced reduction in grip strength with increasing serum NfL levels.