Serum neurofilament light chain in healthy elderly and in patients with age-related macular degeneration

Correlation analysis between smoke exposure and serum neurofilament light chain in adults: a cross-sectional study

BACKGROUND

Smoke exposure is a prevalent and well-documented risk factor for various diseases across different organ systems. Serum neurofilament light chain (sNfL) has emerged as a promising biomarker for a multitude of nervous system disorders. However, there is a notable paucity of research exploring the associations between smoke exposure and sNfL levels.

METHODS

We conducted a comprehensive analysis of the National Health and Nutrition Examination Survey (NHANES) cross-sectional data spanning the years 2013 to 2014. Serum cotinine levels were classified into the following three groups: < 0.05, 0.05-2.99, and ≥ 3 ng/ml. Multiple linear regression models were employed to assess the relationships between serum cotinine levels and sNfL levels. Additionally, we utilized restricted cubic spline analyses to elucidate the potential nonlinear relationship between serum cotinine and sNfL levels.

RESULTS

A total of 2053 participants were included in our present research. Among these individuals, the mean age was 47.04 ± 15.32 years, and males accounted for 48.2% of the total study population. After adjusting the full model, serum cotinine was positively correlated with sNfl in the second group (β = 0.08, 95%CI 0.01-0.15) and in the highest concentration of serum cotinine (β = 0.10, 95%CI 0.01-0.19) compared to the group with the lowest serum cotinine concentrations. Current smokers, in comparison to non-smokers, exhibited a trend toward elevated sNfL levels (β = 0.07, 95%CI 0.01-0.13). Furthermore, subgroup analyses revealed interactions between serum cotinine levels and different age groups (P for interaction = 0.001) and gender stratification (P for interaction = 0.015) on sNfL levels.

CONCLUSION

The study suggested that serum cotinine was significantly and positively associated with sNfl levels in adult participants. Furthermore, current smokers tend to exhibit elevated sNfL levels. This research sheds light on the potential implications of smoke exposure on neurological function impairment and underscores the importance of further exploration in this area.

Neurofilament light chain: a new marker for neuronal decay in the anterior chamber fluid of patients with glaucoma

BACKGROUND/AIMS

Neurofilament light chain (NfL) levels in cerebrospinal fluid and serum are reliable indicators for neuroaxonal damage in a broad spectrum of neurodegenerative diseases. Herein, we investigate NfL levels in serum and anterior chamber fluid of patients with glaucoma.

METHODS

Patients scheduled for routine glaucoma or cataract surgery were recruited for this study. Retinal nerve fibre layer thickness was measured by optical coherence tomography (OCT, Heidelberg Spectralis). NfL levels in serum and in anterior chamber fluid were analysed with Simoa SR-X Analyzer (Quanterix; NFLIGHT, Lexington, Massachusetts, USA). T-test was used for parametric data and Mann-Whitney-U test for nonparametric data. Spearman's rank-order correlation was used to investigate correlations. P values<0.05 were considered as statistically significant.

RESULTS

Sixty patients with glaucoma and 58 controls were enrolled. Serum NfL concentration of patients with glaucoma was similar to serum NfL concentration in controls (median (IQR); 22.7 (18.9) pg/mL vs 22.5 (24.0) pg/mL; p=0.763). A positive correlation of serum NfL with age was observed in both patients with glaucoma (r=0.77; p<0.001) and in the control group (r=0.82, p<0.001). In the anterior chamber fluid, the NfL concentration was substantially increased in patients with glaucoma compared with controls (20.7 (101.3) pg/mL vs 3.1 (2.9) pg/mL; p<0.001). Furthermore, we found a positive correlation of anterior chamber fluid NfL with preoperative intraocular pressure (r=0.39, p=0.003) and with retinal nerve fibre layer thickness (r=0.58, p<0.001).

CONCLUSION

NfL levels in anterior chamber fluid are elevated in patients with glaucoma and correlate with intraocular pressure and retinal nerve fibre layer thickness. The presented data strongly support anterior chamber fluid NfL as a new marker for glaucoma.

Factors influencing serum neurofilament light chain levels in normal aging

OBJECTIVE

Serum neurofilament light (sNfL) is a promising marker for neuro-axonal damage and it is now well known that its levels also increase with higher age. However, the effect of other determinants besides age is still poorly investigated. We therefore aimed to identify factors influencing the sNfL concentration by analysing a large set of demographical, life-style and clinical variables in a normal aging cohort.

METHODS

sNfL was quantified by single molecule array (Simoa) assay in 327 neurologically inconspicuous individuals (median age 67.8±10.7 years, 192 female) who participated in the Austrian Stroke Prevention Family Study (ASPS-Fam). Random forest regression analysis was used to rank the association of included variables with sNfL in the entire cohort and in age-stratified subgroups. Linear regression then served to identify factors independently influencing sNfL concentration.

RESULTS

Age (β=0.513, p<0.001) was by far the most important factor influencing sNfL, which was mainly driven by individuals ≥60 years. In age stratified sub-groups, body mass index (BMI) (β=-0.298, p<0.001) independently predicted sNfL in individuals aged 38-60 years. In individuals ≥60 years, age (β=0.394, p<0.001), renal function (β=0.376, p<0.001), blood volume (β=-0.198, p=0.008) and high density lipoprotein (HDL) (β=0.149, p=0.013) were associated with sNfL levels.

CONCLUSIONS

Age is the most important factor influencing sNfL concentrations, getting increasingly relevant in elderly people. BMI further influences sNfL levels, especially at younger age, whereas renal function gets increasingly relevant in the elderly.