Neurofilament light chain in cerebrospinal fluid or blood as a biomarker for mild cognitive impairment: A systematic review and meta-analysis

BACKGROUND: To allow early diagnosis and monitoring of disease progression, there is a need for biomarkers in mild cognitive impairment (MCI). Neurofilament light chain (NfL) is emerging protein biomarkers in neurodegenerative diseases and is of possible use in MCI. We aimed to assess the utility of NfL in blood and cerebrospinal fluid (CSF) as a biomarker in patients with MCI. METHODS: A systematic search with comparison of NfL level between individuals with MCI and healthy controls were retrieved from PubMed, Embase, and Web of Science. The standard mean difference and 95% confidence interval were calculated using the random-effect model to analyze the differentiation of NfL between patients and controls. RESULTS: A total of 7 studies were included. NfL was higher in 676 MCI than 504 healthy controls. Subgroup analysis according to sample type indicated that differentiation of NfL in CSF between patients with MCI and controls showed significant results but in blood. Moreover, the NfL increasing still existed when the NfL expression level was detected by enzyme-linked immunosorbent assay but single molecule array assay. However, no difference of NfL in MCI between Caucasian and Asian was found. CONCLUSIONS: NfL expression level in CSF was increased in MCI individuals, which indicated that NfL in CSF could be a potential biomarker of MCI.