Morén S, et al.
Low frequency of N-methyl-D-aspartate receptor autoimmunity in tick-borne encephalitis. PLoS One. 2025;20:e0334438. doi:10.1371/journal.pone.0334438
Various viral infections—such as herpes simplex virus—are known to trigger the development of autoantibodies against the N-methyl-D-aspartate receptor (anti-NMDAR).
The NMDAR is a glutamate receptor and calcium ion channel in neurons, playing a key role in synaptic plasticity, learning, and memory.
To date, the prevalence of anti-NMDAR antibodies in the cerebrospinal fluid (CSF) of patients with tick-borne encephalitis (TBE) has not been systematically investigated. If present, such autoantibodies could contribute to the high frequency of cognitive sequelae observed after TBE.
In this study, 53 TBE patients aged 18–65 years with CSF samples suitable for anti-NMDAR analysis were included. A total of 71 CSF samples were examined: 21 from prospectively enrolled patients and 50 from retrospectively identified cases.
The median time from onset of central nervous system (CNS) symptoms to CSF sampling was 91 days.
Only one of the 53 patients (1.9%) tested positive for anti-NMDAR autoantibodies, with two positive CSF samples collected 27 days and 433 days after symptom onset.
Given the high prevalence of cognitive complaints following TBE and the very low frequency of anti-NMDAR positivity, the authors conclude that other mechanisms—rather than NMDAR autoimmunity—are likely to underlie the majority of post-TBE cognitive sequelae.