Serum neurofilament light chain in patients with epilepsy and cognitive impairment

Abstract Background The neurofilament light chain (NfL) is receiving increased attention as a biomarker of neurological diseases, as NfL concentration elevated in the blood and cerebrospinal fluid after neuronal damage. However, few studies have addressed NfL in epilepsy. We aimed to investigate the alteration of serum NfL in adult patients with epilepsy, and the association between this biomarker and cognitive impairment. Methods A total of 38 consecutive patients with epilepsy and 24 controls underwent cross‐sectional measurement of serum NfL levels and cognitive testing using the Mini‐Mental State Examination (MMSE), the Japanese version of the Montreal Cognitive Assessment (MoCA‐J), the Frontal Assessment Battery (FAB), the Trail‐Making Test, and the Stroop Color–Word Test. Statistical analysis was performed with Student’s t ‐test to compare serum NfL levels between the epilepsy group and the control group, and with Spearman’s correlation and age‐corrected partial correlation analyses to evaluate the association between serum NfL level and cognitive impairment in epilepst patients. Results There was no difference in serum NfL levels between the epilepsy and control groups (epilepsy [mean ± SD]: 17.3 ± 13.9 pg/mL; control: 17.7 ± 11.5 pg/mL; p = .92); however, the MoCA‐J scores were lower in the epilepsy group (26.6 ± 3.1 vs. 28.1 ± 1.6; p = .03). The age‐corrected partial correlation analysis showed a correlation between serum NfL level and cognitive test scores in the epilepsy group (MMSE: r s = −.63, p < .01; MoCA‐J: r s = −.54, p < .01; FAB: r s = −.68, p < .01), whereas serum NfL levels were correlated exclusively with MMSE scores in the control group ( r s = .44, p = .04). Significance In adult epilepsy patients, the serum NfL level was not significantly elevated, but was correlated with cognitive test scores. Our findings suggest that serum NfL concentration could be an indicator of cognitive function in epilepsy patients.