Association between serum neurofilament light chain levels and sleep disorders in patients with Parkinson's disease.

Objectives: This study aimed to investigate the levels of serum neurofilament light chain (NFL) and glial fibrillary acidic protein (GFAP) in patients with Parkinson's disease (PD) and PD patients with sleep disorders (PD-SD), as well as the relationship between these proteins and sleep disorders in PD patients.

Methods: A total of 96 PD patients and 38 healthy controls (HC) were included in this study, of which 70 PD patients experienced sleep disorders. Both motor symptoms and sleep conditions were assessed in all PD patients. The ultrasensitive single molecule array (SIMOA) technique was used to quantify NFL and GFAP in the serum. All data were statistically analyzed using SPSS 23.0.

Results: Serum NFL and GFAP levels were significantly higher in PD patients than in HC. Similarly, PD-SD patients exhibited higher levels of these two proteins than PD patients without sleep disorders (PD-NSD). In addition, both serum GFAP and NFL were significantly associated with sleep-related scales in PD patients. After covariate-adjusted binary logistic regression analysis, NFL remained statistically significant in PD patients with or without sleep disorders, unlike GFAP.

Conclusions: Our findings substantiate that serum NFL and GFAP levels are elevated in PD and PD-SD, suggesting neurological axon damage in PD patients, which may be more severe in PD-SD than in PD-NSD. These findings may affect disease diagnosis and provide the foothold for future studies on the underlying mechanisms.