Cerebrospinal fluid biomarkers in SARS-CoV-2 patients with acute neurological syndromes.

BACKGROUND AND PURPOSE: Mechanisms underlying acute brain injury in SARS-CoV-2 patients remain poorly understood. A better characterization of such mechanisms remains essential to preventing long-term neurological sequelae. Our present aim was to study a panel of biomarkers of neuroinflammation and neurodegeneration in the cerebrospinal fluid (CSF) of NeuroCOVID patients. METHODS: We retrospectively collected clinical and CSF biomarkers data from 24 NeuroCOVID adults seen at the University Hospital of Guadeloupe between March and June 2021. RESULTS: Among 24 NeuroCOVID patients, 71% had encephalopathy and 29% meningoencephalitis. A number of these patients also experienced de novo movement disorder (33%) or stroke (21%). The CSF analysis revealed intrathecal immunoglobulin synthesis in 54% of NeuroCOVID patients (two with a type 2 pattern and 11 with a type 3) and elevated neopterin levels in 75% of them (median 9.1nM, IQR 5.6-22.1). CSF neurofilament light chain (NfL) was also increased compared to a control group of non-COVID-19 patients with psychiatric illnesses (2905ng/L, IQR 1428-7124 versus 1222ng/L, IQR 1049-1566). Total-tau was elevated in the CSF of 24% of patients, whereas protein 14-3-3, generally undetectable, reached intermediate levels in two patients. Finally, CSF Aß1-42 was reduced in 52.4% of patients (median 536ng/L, IQR 432-904) with no change in the Aß1-42/Aß1-40 ratio (0.082, IQR 0.060-0.096). CONCLUSIONS: We showed an elevation of CSF biomarkers of neuroinflammation in NeuroCOVID patients and a rise of CSF NfL, evocative of neuronal damage. However, longitudinal studies are needed to determine whether NeuroCOVID could evolve into a chronic neurodegenerative condition.

A combination of total tau and neurofilaments discriminates between neurodegenerative and primary psychiatric disorders.

BACKGROUND AND PURPOSE: Neuropsychiatric symptoms are commonly observed in neurodegenerative diseases. No biomarker is currently available to diagnose psychiatric conditions. As a consequence, the distinction between psychiatric and neurodegenerative disorders can be challenging in daily practice. METHODS: This retrospective study included a cohort of 64 primary psychiatric patients (PSY) and 162 patients suffering from various neurodegenerative disorders (NDG). Total tau (t-Tau), phosphorylated tau (p-Tau), Aß1-42 peptide (Aß1-42) and neurofilament light chain protein (NfL) were analysed in cerebrospinal fluid. The discrimination between PSY and NDG patients was assessed using both individual and combined analysis of cerebrospinal fluid markers. RESULTS: Cerebrospinal fluid t-Tau and NfL exhibited the best diagnostic performances: they were able to discriminate between PSY and each subgroup of NDG patients. t-Tau had the highest sensitivity (93.8%) but a poor specificity (67.3%). Indeed, some NDG subgroups exhibited low t-Tau levels comparable to PSY patients. A sequential combination t-Tau + NfL improved the characterization of patients, especially in these particular subgroups, increasing specificity up to 89.6% without modification of sensitivity. Finally, this combination of markers led to a high classification rate of 90.7% for the whole cohort of patients. CONCLUSION: The sequential combination t-Tau + NfL enables the biological detection of neurodegeneration in patients with psychiatric features. This association of markers seems to be a promising strategy for a differential diagnosis in clinical practice between primary psychiatric conditions and neurodegenerative disorders, thus improving medical care of patients.